Hi,
I'm back here overcomplicating things so instead of trial and error that can't easily be undone I'm hoping to find some experience. I'm building a hodgepodge 57 ranchero, manual trans 292"+ with cam (of inappropriate design), cleaned up b intake manifold (or something stupid made from aluminum), g heads mildly ported, making a set of long tube (fender exit, 180° tri y, 8:1 depending how the tubes fall). Porting on the exhaust side should I port match to gasket shape, leave the one angled corner (should header port try to match that shape), braze in that portion to level the floor (could be a chance to raise the roof). For the headers should the flange be matched to the port or slightly oversized (supposedly reduces reversion to valve), 1 5/8 primaries seem appropriate (although unable to find any good calculators on length, tube sizes after Y's, collector sizes) Would using an appropriate size and length collector extension dumping into a larger exhaust significantly hurt the power over just running the open extension or transitioning into dual 2" full length exhaust.  It seems to be held that larger exhaust does add some base to exhaust note and ive got 3" exhaust sitting in the garage. thanks
Seth

I was pretty conservative with the porting-took my time, looked at lots of photos (including John Mummert's cutaway views), and did a lot of reading as well. However, I'm a long-time believer in Murphy's Law. I'll be celebrating my 70th birthday (maybe "celebrating" isn't the best choice of words) next month. It's a little late in life to start being optimistic.  

6 VOLTS/POS. GRD. NW INDIANA