Knowing that a T56 will mate with a SBC perfectly, will it mate with a BBC?

 

Bellhousing mount bolts, yes. Flywheel, no. A BBC flywheel is different than a SBC. The 454, 502 etc engines are externally balanced and need a specific flywheel with a counterweight. The 396, 402, 427 are internally balanced.

You could put the T56 behind a BBC if you buy the proper flywheel for it.

 

Have you looked at the McLeod "universal" bellhousing, for adapting virtually any manual trans (including the Viper T56) to any engine.

http://www.mcleodind.com/catalog_htm/PAGE6.htm