This is what I would do Tom. It's not going to disort (without the top skin) enough to make a difference. The only thing that really matters is that you leave enough material so that your edge distances for the screws will be maintained. IIRC, I just tried to keep the same amount of overlap around the top as there was down the side width. Beyond that, just make it look nice, e.g. symmetrical on both sides. Good luck.Thanks Steve, I was mostly asking how to best determine where to make the cuts. One option I can think of is to trace the opening from the rear of the 706 bulkhead, then measure a distance from that line. For that I'll have to un-cleco the top skin which may distort the opening a little.