Chris,
I don't know how familar you are with olds..every small block olds used two openings on the RH manifold. The RH manifold in the front towards the front of the car has a 2" opening that is normally the single outlet from the crossover on the left manfold when used with single exhaust. That single outlet gets capped for dual applications just like the factory W31 Olds 350 cars. The rear outlet is 2 1/2 and take a triangle clamp.
The new pipes are mix of Pypes and Torque Tech. The downpipes from TT are not exactly what I would do again as they required a lot of cutting and the left did needed to be about 1 inch lower to clear the neutral lock-out linkage. I had to "dent" the top of the drivers pipe to get the linkage to work....no biggie, but could have been better.
Here is the old system that was done at a local shop. It shows how we welded shut the front 2" opening. GM used to make a blank-off for it.
I think you will find this information and photos valuable. I would be willing to discuss in more details if you drop me a PM. We can discuss again working something out for the 403 guys.
