['ol Pinion head]

Several years ago, RARE offered round port exhaust manifolds for '64-67 models. Might be worth calling Paul & see if more are in the works.

My earliest acquaintance with round port manifolds in an early chassis A-body was in the late 80's. Local '65 GTO owner took a sawsall & an angle grinder to the driver side cradle then pieced in two pieces of plate steel. Finished up welding them in with a crackerbox welder, then installed his .060 428 with RA2 heads. IMO, created a lot less issues than moving the engine/frame stands back.