please help picking motor..

Like I said . Not all 318 polies are changeable. you would have to get casting #. A good place to get answers is The H.A.M.B forums. These guys have about a 1000 years of knowlege between them as far as old Hemis ,polies. They will let you know what is and isn't and what to stay away from. anything Hemi is spindy . I was about $8000 into my 354 before the smoke cleared. Actually you would be money ahead if you took that 318 punched it out to 360. Back in the day the 360 was the engine of choice, it bested alot of BB Chevies and ford and probably would be cheaper to build.