I think $1700 sounds like a pretty good deal. Where are you located? I have a Max IV body and frame I can sell. The lower tub is very nice, and the upper only has holes for stock accessories in it. I acquired the machine, and it wasn't complete enough to be worth putting back together. The hulls on all Max IV's are hdpe. I do not recall the exact engine options for that year, but they used several over the years. The RIM (predecessor to the IV) used a g50b in it. Then when it was the IV, they used the kawi 440a, the Tecumseh OH series, the kohler commands, the vanguard series Briggs, the Kohler Magnums, some some Kawasaki twin 4-stokes. And for your first question last, patch the hill by plastic welding, or get a new tub. Fiberglass on plastic doesn't hold up, and on hdpe is a joke. You can get caplugs on eBay or from Mudd-Ox(Max). They are cheap and considered disposable by many.
l like to buy stuff and no I don't do payments!