This is known as hotrodding ! Change one thing/ have to change 3 other things !
I ran dougs headers on a 67 hemi belvedere, they were hard to get on, but fit perfect. I run tti`s on my 505" 68 fastback w/ raised port heads and everything is close but clears everywhere . Bought them used and cut 1 and 3 tubes out , drove 1 7/8 ball thru them and re welded back in, to straighten them back out from the previous owner, do not know the exact part# even .
Gaurantee they wouldn`t fit w/ torsion bars tho !