Its been awhile but Im making some progress again. Here a couple of engine pics with mock up of stainless headers.
This is the ZZ427 crate engine that GM says is 480 hp and 490 tq. I dynoed it last Sat and it made 526 hp and 518 tq.
I changed the oil pan and added a very good Miledon windage tray, used the tri-y headers shown and a 1" carb spacer. Spacer added 10 hp and 9 lbs tq.