I don't know about kits, but I was involved in a group buy over at .org. We had a batch of 4-spd slant bellhousings modified to run a Mustang T-5. Still have to come up with clutch linkage and fabricate a lower crossmember and notch the upper crossmember, but here's hoping someday...
There's also a guy named MPGMike who puts together turbo setups for slants. I think these are as close as you'll get to "kits".
The Supercharger Store has a blower kit for the slant. It's not cheap, but if I had the $$$$, and was willing to give up my power steering... Contact them if you've got $3-4K to spare!