Find a master with 1 inch or less bore. The 81 TA uses the newer style aluminum master that is 25mm bore. Brake proportioning valve from a 1977-1978 Seville with 4-wheel disc. The newer style masters have the lines reverse. Brake vacuum booster from 1983-1987 Regal/Cutlass works with the newer style masters and bolts to our trucks. I have all this stuff but have yet to take on the conversion.
Good place to look up master cylinder bore diameter
www.partsamerica.com
good info here
http://home.pacbell.net/bigiron/Arti...rRearDisc.html