Upgrades for older max ii?

[Dw89xj]

I just bought my first max ii, an 84. I've already made a deal to sell the 440 jlo 2 stroke and switch to a 4 stroke, my budget won't allow for a brand new engine at this point but I've had my eye on an opposed cylinder 18 horse Briggs.
My first question is will the opposed cylinder Briggs be a simple swap or is it a pain because of the cylinder arrangement?
What clutch should I run? Is one preferred over another or just stay away from Chinese junk? Also how much shaft do I need for said clutch? I'm finding engines wth 1 1/2-4" shafts.
Would I be able to upgrade to newer stye bearings and axles without alot of fab work? And would it be worth it or should I just upgrade to solid axles and bearing cages and keep it greased and stick with bushings?
I'm planning adding electronics like a stereo, led lighting, winch, power ports, maybe even a small inverter. Is an alternator going to take much power or won't make that much difference? I want to go with no less than 18 hp but depending what deal I find I may go as low as 14hp for the time being.
Fuel cell - are there any good ones floating around in southern Pennsylvania or should I just look at getting one of the hot rod ones from eBay? What are the dimensions on a factory round fuel cell? Mine doesn't leak but I'm not a fan of a home made cell with a pipe cap for a gas cap, or the sharp corners and slag to get cut on in the unfortunate occurance I flip or roll this thing.
Where is the best place to get sheets of hdpe online? I have a patch to make I didn't notice in the dark when I picked it up, I know never shop for vehicles in the dark but after 5 hours cooped up in my van and it being a running machine I just wanted to get loaded and head home. Also I want to make a one piece skid plate to go from front to back.
Is aluminum much, if any heavier than hdpe? I'm wanting to build a new bed from diamond tread that follows the factory body lines and bends and doesn't stick past the original body. I may break down and see about buying the upper in the parts forum but I'll cross that bridge when I get there.
I have a geo tracker soft top I'm going to attempt to use as a topper also, If it's not too terribly wide compared to the max. It might be kind of nice having a choice to have the bed closed in or run without back windows like a bikini style. Another bridge to cross at a later date . I'm going to start tearing the upper body and bed off tomorrow and get it jacked up and assess what all needs attention before I dig into the "fun" stuff that I don't need.
Thank you all for all your help.

[philipatmaxfour]

Dw89xj, Hello my friend.I like the sounds of your plans. You have lots of questions and that is good. I will let others with more experience deal with your other questions but as to your skid plate material, it is pretty much unanimously agreed that you cannot beat hdpe and aluminum is not slippery enough to slide over objects like rocks. Welcome to the amphibious addiction. Ps: If you turn your tires around they will work better in the water

[Dw89xj]

Dw89xj, Hello my friend.I like the sounds of your plans. You have lots of questions and that is good. I will let others with more experience deal with your other questions but as to your skid plate material, it is pretty much unanimously agreed that you cannot beat hdpe and aluminum is not slippery enough to slide over objects like rocks. Welcome to the amphibious addiction. Ps: If you turn your tires around they will work better in the water

I apologize I should edit that, I'm wanting to make a new bed from aluminum diamond tread, someone before me cut it down similar to a lil truck, and the angle and expanded steel bed sticks past the body 2 to 3 inches on either side. I definitely want my skid to be hdpe though. Thank you very much for the insight. Is the hdpe any more difficult to plastic weld than say a car bumper cover? That's the only plastic welding experience I have. The worst spot is behind the left rear wheel it looks as though an access cover was cut for the clutch then patched with mud flap and black jack. As for tires I need a couple they are badly dry rotted but they will be turned the right way for swimming when it happens, I just wish they weren't so salty, I found knock off strykers for $120 for 3 but from what I gather that style doesnt swim very well at all.

[philipatmaxfour]

There are many pages of opinions on welding hdpe on this site. Most people seem to have good luck . Some people just use a strip of the same material and a soldering iron. Others are happy with a proper welding gun. Good luck.

[Dw89xj]

That's how my boss had my fix bumper covers, was with a soldering iron then sand it and fill the low spots and he would do the rest. I'm not terribly concerned with how it looks as long as it's strong and water tight. Like cold weather I don't want my repairs cracking out.

[dirtdobber]

As far as plastic welding use a proper heat gun. I've used both the soldering iron and heat gun and a critical repair with the soldering iron failed. The heat gun allows you to maintain heat over a larger area and achieve a better repair.

[Dw89xj]

As far as plastic welding use a proper heat gun. I've used both the soldering iron and heat gun and a critical repair with the soldering iron failed. The heat gun allows you to maintain heat over a larger area and achieve a better repair.

Thank you that's good to know, on the bumper covers it was just cosmetic so it wasn't as critical to be strong.