6/7 Speed Freewheel To 8/9/10 Speed Cassette Bike Conversion

I upgrade my vintage road bike from 12 speed (2x6) with downtube friction shifters, to 16 speed (2x8) with STI brifters. This process includes expanding the rear triangle (chain stays/seat stays) from 126mm to 130mm between the dropouts so the wider wheel will fit in the dropouts. You only want to do this on a steel frame! I also replaced the wheels, derailleur, crank set, cables, housings. I also convert from a quill stem to a threadless stem, because it was convenient. I could have just as easily upgraded