Hi Jeff,
One of the issues I see with the Tremec is that the transmission mount is about 2" further to the rear than your toploader. In your Contemporary, the transmission mount is welded to the frame crossmember so an adapter might have to be fabricated that could bolt to your existing frame mount and extend rearward the required distance for the Tremec. The other alternative might be to cut the existing crossmember, flange it so that it is removable, and move it rearward. Your current Lakewood bell housing should be sufficient, and I know that Forte's Parts Connection (
http://www.fortesparts.com/index.cfm) at one time sold a TKO specifically for the FE motors with a shorter input shaft (26 spline) so that a tranmission to bell housing spacer was not needed. They may now have a 10 spline shaft that is the correct length so that you wouldn't have to change out your new clutch disc. Anyway, Buddy said that you could bring it by his garage and we could take a look to see what all would be required to replace the toploader with a Tremec.
Cheers,
Reed