I don't think 3.73 gears are deep enough to run with a 6 speed. You might need something in the 4.50 range. If it was me I'd shoot for an overall final gear ratio of 3.55 in 5th and then something around 3.0 in 6th. This all depends on tire size and the torque curve of the engine of course. The second OD in 6th gear is so high that it kills most performance engines. You end up lugging the engine down the freeway with a performance cam. The OE's get away with it since they have variable cam timing. We don't have that cool stuff so we have to compromise.
I agree with you on the gearing. I have a 6 speed with a .63 6th gear. with 3.91’s and a 26” tire, the happy spot in my car was ~90mph in 6th. Cool and fun, but not conducive to keeping my drivers license. Driving from San Jose to willow springs was mostly a 5th gear deal. Especially over tehachapi going into Mojave. I’m thinking of going to a 4.10 or 4.30. Tremec has a good calculator that has gear ratios for the popular transmissions built in which helped me out a lot.
