<VV> Porous aluminum?

[shortle]

Awhile back I read here about someones attempt at fixing oil leaks on their Corvair.
I also have a slight drip coming from my bell housing and I would like to fix it. I plan on replacing the bell housing seal with a Viton as well as a new bell housing gasket. I will install 2 clutch shaft seals in my diff. "snout". I also have a new retainer to hold those seals in.
What other precautions should I take? I read about sealing the flywheel bolts as well as the correct bell housing bolts. This is the only leak I have on my car. Could the bell housing casting be porous? This is on my '62 Monza Wagon 4 speed, 3.27 diff. (both '62) and a 110 RH engine. Thanks to all for any suggestions.
Timothy Shortle in (beautiful, windy) Durango Colorado 81301