Try http://www.quicktimeinc.com/products.html for a SFI blow-proof rated, spun-forged bellhousing.
I have RM-6071 MOPAR Bellhousing/TKO 500-600/T5 Mustang/TR3550 for my upcoming T-5 swap. You may be interested in RM-6070 MOPAR Bellhousing/Chevy Transmission if you are sourcing a Holden...