[zipzip]

I did the grind job on my headers to smooth out the transistion. There was some pretty large weld beads on the inside of the header tube. For my 302, larger diameter tubes were out of the question to leave clearance for the bolts - the tubes were already flattened to be able to fit the bolt! I'm not concerned with failure because there is still weld filling the interface between the tube and flange and for equal thicknesses, weld will hold up longer than the steel tube anyway. I think a good blending job will be more important than making the holes match exactly. Take as much out as you feel comfortable with, up to flush with the inside of the tube, then make a nice smooth transition.

Todd