My new small block Mopar (not an A body)

318-3 definantly had a forged steel crank, you see them for sale, ie "318-3 steel crank" and if it had a smaller spark plug thread , it may have enlarged water jackets that surrounded the plug for better cooling. If you travel alot and plan on putting a few thousand miles on it a year, you might consider a Cummins transplant. It may pay for itself in the long run with double the mileage and maybe a little cheaper per gallon on the highway. We rented a 440 powered poptop Dodge conversion van once and that thing hauled the bacon big time. We were passing cars on grades and my dad was giggling the whole time.