MAGNUM PAN ON LA ENGINE

I'm having a problem with the 1-piece Magnum oil pan gasket sealing to the timing cover.
I could fill the void with silicone sealer, I try to use as little as needed.
We run a Magnum truck pan "rear sump" on a stock eliminator car.
It doesn't seem to have enough crush to seal, the back seals fine.
Suggestions?