Both holes are now cut and opened out correctly in the body. The collectors have been on and off half a dozen times or so trying to get the clearance neat and equal all round, but the holes now seem to be correct.
There have been issues on both sides trying to get the collectors far enough onto the headers to allow them to run parallel to the car. After tightening up the header bolts, and pushing, shoving, swearing and employing the carpet and hammer trick I still couldn’t get them closer than comming out to corner just over 2 and a half inches from the body whereas I needed that gap to be about an inch. Looking for alternative suggestions I found a forum post that recommended just chopping a little off each header pipe’s end from the man that made them so after doing just that, they’ve gone on and now fit perfectly.
They need to have a self tapper put in place on each side, from the headers to the collectors to stop them dropping during use and I need to pick up a couple of powder coated brackets from Dax to allow me to tie the back of the exhaust to the chassis using two large rubber bobbins as vibration dampers.
Now onto the pipework for the engine and getting the thermostat in place and water-cooling all linked up…