driveshaft length, ls-1 t-56 to 2 pc rear main block

[68protouring454]

hey guys, am wondering what you are getting for driveshaft length when getting shaft made up for your first gen camaro when doing this swap, i have a chance to get a killer deal ona dennys shaft and as long as it longer, they shorten it for free, let me know.
car is a 68 camaro
454, mcleod modular housing,ls-1 t-56, ats crossmember, going into a ford 9 inch
jake