Yeah, when I had mine built they used a 73 valve body and a later style tail housing to allow the use of large yoke. Also went with factory GM deep pan and filter extension.
didn't read all post, but a good ST 400 with convertor and short shaft is cheap at $600 shipped. I have one in a 67 Skylark I'm thinking of selling whole car or parting but would not sell for that.
You are correct. The '65-'67 SP400's valve body tends to short-shift third gear, and there is no 3-2 downshift valve, meaning it doesn't like to kick down at much less than full throttle. Switching out to a '70-'74 BC (Big Car) valve body gives you those advantages back. Give this article a read. http://www.buickperformanceclub.com/SPTrans.htm
If I can figure out an easy way to package and ship the thing I have a brand new fully updated 67 switch pitch 400 with a tri Shield converter I would sell.
I just shipped one through fastenal, actual sitting in lot still at fastenal as I read this. From Ohio to Utah was like 200ish, and I had to buy a skid, pay to have it banded and weigh, plus my time running back and forth to few places. But was an easy procedure
