A two bolt main block is more than adequate for street use unless you turn high rpm or haul heavy loads. Most passenger cars had two bolt main blocks and they performed very well.
BTW If you had a large journal 302 crank, put it in a 307 block with 283 Pistons viola large journal 283.
Small cubic inch and high rpms do not make make good street engines IMHO. A 383 small block stroker with vortec heads and a four barrel throttle body injection mild cam and small cap HEI would be the berries in any of these old trucks.
Just sayin'
