Looking for some basic mods?

2.45's are super uncommon around here but we're ready to be served up out west. The 2.45 IIRC came more so standard in The gas crunch years. 2.76 was the common Hwy.gear here. Metro-ish area.

The 340/360 ports are larger. Intake wise, the Performer has smaller ports. Actual size on other intakes should be looked up & known Before purchasing.

Agreed on exhaust manifolds over headers.
Use a split duration cam here. Comp Cams has a line designed just for exhaust manifold engines.
I agree I exhaust sizing. A decent designed X pipe and a pare of turbo mufflers is all you'll need.