Sounds like the $ savings is in the block. The ZZ502 features 4 bolt mains and forged 1052 crank which is slightly more robust compared to the 2-bolt/cast combo.

However, the lower ends on 2-bolt cast crank BBC's are typically plenty good for 650+ horsepower. The price you gave is extremely attractive. I have a comparable ZZ502 with about a 50 HP upgrade via porting/cam combo at just under $9500.

Looks good to me ..................

Regards, Kitz