2&1/8" tti in 73 duster

Schumacher mounts , unsure what biscuit mounts are . Its a manual steering car

Buckmaster did you follow the install instructions that came with the mounts?

http://www.engine-swaps.com/IMGs/Instructions/73 & up V8 - BRB4.jpg

I had to do it with my 73 dart, but i was only using Indy EZ heads and the TTI 2x3-1/2 headers. I take it you are using INDY SR or 440 Dash-1 Heads? got any more pics of your car? sounds like it will be a very nice car when you are done.