T56 Install - Factory Crossmember Modification

[ModernMuseum]

I've read a few places that I could use the factory cross-member in my 1969 firebird for my LS2/T56 install. I've heard that some people have installed it upside down and used a ~2" spacer to retrofit to the T56.

Does anyone have any details on their install or details of the spacer block using this method? I'd like to have the cross-member ready for when I get ready to stab the engine/tranny in. Thanks.