repowering my 1986 Liberator

Here is what I have. 1986 Liberator 211, I bought it this summer and ran it. It did fine with my wife and I but put anyone else in it the it is a dog. The guy I bought it from re-powered it with a 305 that he "built up" I am sure it is just a auto engine had auto carb, fuel pump, dist and so on. I am not impressed with his work at all since I had to just about rebuild the engine. Now my question is do I just pull it and put a 350 marine engine in it or..... (this is what I get for thinking and looking on these websites) drop a 383 stroker in it? If I do the stroker how long will the alpha last or should I scrap that as well and put a bravo in it? If I put the bravo in it how hard of a conversion is it?

Thanks,
Ken