you can also track down a large journal 302 chevy crank. or you can ahve a 327 if you use a 307/327 crank in your 350 block. i run a 283 bored .125 over i like these little motors alot but have never done it the way you are trying. i would try to find a 302 chevy crank. you can get aftermarket ones now for about 500ish i belive not a bad deal. whats the casting numbers on those heads?????

couple of quesitons

whats the main purpose of this motor? race track? street?
what kind of car is it going to be put into?
what kind of heads, cam, and intake did you have in mind?
what do you want out of this motor?