A decent Mark Twain V 18. I am just not sure what to offer.
Being the 18' probably their Tri-Hedral hull which amounted to a V monohull with short sponsons......not your conventional Tri-hull with it's rough ride in a lot of cases. Will ride rough water much better than your aristocratic Aristocraft and more stable at rest, better "bow" access for anchoring, docking, riding and all.....things to consider. Very popular around here in the 70's and 80's. Very smooth dry ride in rough water (what was the norm around here), very stable at rest, lots of room for the family and gear; super boats for the family. 165 L6 would push it in the upper 30's, the 5.0 V8 over 40.
Start low. Guy asked me to quote a non running tractor once. He said it had no oil pressure last time it ran. I hoped for the best, got the worst, but sold the loader for half what I paid for the tractor and the deal sweetened up. If he's serious he won't get offended by lowball offers. If he refuses your offer, just walk away........slowly. If he doesn't hit, drive off and have a cup of coffee or something. Come back and inch your offer.....plead with him like.....Look man, I only have so much money. This is an old boat. I don't know what I'm getting into. That sort of thing. What's the gamble is worth to you? The place to stop your bidding. Good luck.