Manifold to pipe issue: HELP

After attempting multiple flanges, gaskets, etc, (and even trying to make a flange), I cannot get a good seal between the exhaust manifold and the exhaust pipe. A friend of mine, who is a knowledgable mechanic, has also assisted, with no luck, (its nice that he can try different flanges and pipes and send them back, no questions asked!).
There is just nothing that will press the gasket down completely, and eventually the gasket fails.
The last resort is a new exhaust system, but there is no guarantee the flanges will be any better or different.
I have a 67 383 4 speed, so headers are not an option either, (at this time as I would have to spend $400-$800, and I still have to modify them for the linkage).

I've sealed the firewall, put a new trunk seal on, etc, but the exhaust gets in the car, and when I open the windows its worse.

The exhaust is making me ill- any solutions?