So....based upon testimonials on this BB regarding the ONLY headers that will fit on my 454/70 Jimmy combo without frame chopping, I went and made the leap of failth and purchased the '67 Chevelle Hedman 'hedders'. Upon removing the stock GMC exhaust manifold, I noticed an issue right away. The exhaust ports on the heads were squarish, the headers were round port. Panicked, I quickly searched the web. I noticed that every set of headers available, from all mfg's, were round tubes. Also noted with keen interest that the Hedmans pretty much across the board have round holed gaskets, and the Hookers have square-ish gaskets even though the header ports are round. From this I concluded that there really was no issue here and commenced to bolt up. Was this conclusion erroneous? Second question: These Hedmans seem to be a little on the cheap side. By that I mean construction wise. Whereas the bolt pattern was an exact fit, the 'mating' surface was less than flat. Tubes protrude past the flange face by about 1/8 inch on average. Warnings abound about don't alter, grind, bend, deface, bla, bla, bla or the warranty will be voided. Would like to get other's take on this please. Final question: The old stock manifolds were 'connected' to the exhaust pipes at the collector via the traditional 'doughnut'. I received with my header kit a flimsy little gasket for this interface. Is this appropriate? Should I discard the gasket in favor of new 'doughnuts'? Thanks!!