I am going a different route and will be pulling the engine/trans out of my 69 Camaro soon. I have a cool set of custom pace setter headers custom built to fit with the BPR motor mounts and a steeroid rack system.
They are ceramic coated black and have about 10K miles. We welded a ball clamp assembly to the collector so they bolt up like a factory system with no gasket or leaks.
$450 + shipping obo
They still have to come off the car, so expect up to two weeks before I can ship.
The passenger side required no mods except adding the high quality collector. The driver side required three tubes to be moved.
Pipes are 1 3/4"
