Early Abody Doug’s 450 header install BEFORE engine going in

The torsion bars have to go between the tubes on both sides of the D450's, so OP's plan should work just fine since his torsion bars are already slid back. As a follow-up question for @66fyssh and others that have them, would it be a good idea to go ahead and cut the headers flanges before putting them on the first time? My D450's are all intact, but the flanges are cut about half in two between 1 and 3, 5 and 7...and 2 and 4 and 6 and 8 on the other side.