I have the same ideas...i also have a 70 convertible fremont built...would like to change to 3:55's in the rear and install a 200 trans, spoke to a guy hear in sacramento this week who machines a lot of internal parts for many of the shops you mentioned.. if you want one of these trans to operate properly, a pro needs to set up and do the final tune...i still want it but its $$$$$...let all us know what u decide.
http://www.ptsnctb.com/