Chevy man~~~~Caddy?
I've been a Chevy man since my first car--'53 Chevy>'65 Corvair, SBCs etc. I've built dozens of SBCs for myself and others and had the parts for a 6" rod 350 on hand when I got this Caddy bug--cheap horsepower and unbeliveable torque! Also, I have done so many SBCs a change was appealing and this is turning out to be as much fun as my first engine rebuild was in the mid-sixtys. I've disassembled many SBCs--always required a ridge reamer to remove the pistons, none of the Caddy motors even had a ridge!
I looked, the HT 502 certainly looks impressive but still less torque and horsepower than the 1970 Caddy. Several sources that I've read say that in towing applications the Caddy gets 7-8 mpg better than 454. I don't know how the 502 compares to the 454.
The castings on the Caddy are unbelievably light and consititent and the heads had heart-shaped, low-crossflow combustion chambers in 1968--years ahead of Chevy and I guess the source of the design.
Anyway, either one will get the job done.