Do the V8 motor mounts swaps or do I have swap the k member would like 3 inch exhaust not sure what size headers I need also what is good rear for 350 horse 4 speed trans what parts do I need
For Street and limited Highway use a 3.91 gear is good, or 3.73.
There are bracket kits to swap n retain the k member.
1 5/8 primary to 3 in collector headers would be fine. You already have the pedals in the car so you will need a four-speed shifter, a floor hump, and bell housing and corresponding clutch and flywheel which would be a 10 and a half