the block was much heavier with full webbing for the mains allowing 4 bolt main caps , this offered the Potential to make a lot more power with the small blocks although I really have never sens a T/A block taken out to max performance . These were followed by R3 blocks in the early 80s , which are extremely strong !
the Heads were very different as well , the intake port was identical as cast But the pushrods were moved over so the heads could be massively ported if desired , as above all the of the valve train is unique to these heads .
All of this was a first step , it was followed with the W2 series heads in the early 70s which are much more radical , then followed the W5 alum & the W8 &9 heads
I heard of a lightened Prostock Mopar with a R3 /W9 running Prostock times a couple of years ago so what 800 HP or so ?