small block heads, 4027596 casting # any good??

You will make much more usbale power by having the heads redone properly than by cutting corners and trying to port them too. You dont neede ported heads to run deep in the 12s. If you assume they will need guides, valves, springs, locks, retainers, guides trimmed, spring seats cut, and milled... you're close to reality. The 5-angle valve job does about 60% of what bowl porting does anyway. Be realistic in the build and you won't be disappointed.