Thanks for taking the time to write that John - appreciated
I don't argue with any of what you've written - the 70mm tb is something I would change if starting again for sure (back to 60 or 65mm max). On a small displacement engine with a large tb, making part throttle behave nicely is a real pain (by part throttle I mean the first 1-2% opening). Crawling along in traffic on/off throttle territory.
You've hit the nail on the hear re the warped manifolds - they do use a jig but I think what they should do (IMO of course, I'm not a metal worker) is use a much thicker flange (half as thick again perhaps) and mill it down once finished. So factor in the (less) warping due to the thicker flange, then mill it snooker table smooth. But of course, that costs money and a little extra time.