Yes, Mopar BB heads are very small compared to something like a BB Chevy head. That is why it is easier to make power with a big BBC than a big Mopar BB. The TF270 heads provide the average backyard builder with a good 700 head. A pro engine builder can get 800 hp out a set of TF270 heads but it gets hard to make more than that NA.

If you want to run a BBC then you can buy a 1000 hp pump gas street engine. The BBC has become a much better engine for making power over the last 30 years because GM has continued to upgrade the design. Mopar never upgraded the big block design so we're still stuck with two piece rear main seal and other outdated features. I have a customer with a Mark VI big block and it has substantial upgrades when compared to the muscle car era design.