5 or 6 speed manual behind new Hemi - Realistic Options?

After driving an '09 Challenger 5.7L 6speed with it's 28.6" tire, and 3:91 rear end, I bought a 5 speed TKO and bellhousing for a Gen3 Hemi for ~$1500. Found it on craigslist. A gent bought it new, but never installed it in his mustang. The newer Challenger is geared super short in 1 and 2, and 6th is too tall for me. Great for fuel economy in the newer, heavier Challenger, but not for my '67 Dart project. I think the ratios in the TKO I bought should work well with the 3:73 rear end and ~27" tire i'm planning on.

FYI - the viper 6 speeds have a taller first gear than the 6 speed that's in the Challenger. Viper is 2:66 vs 2:97 in the LC