Stroked66 recommended a guy who could build me a T5 that could handle my 347. He says that 5th is .59, I was wondering if anyone had this 5th and what they thought of it. It will probably have 3.55's or so.
I don't have a 5spd (yet), but with this setup you will have 34.4mph/1000, near what you'd have with a std WC T5 with a 3.00:1 and 0.68 5th (35.3mph/1000) and equivalent to a 2.07 rear in my T10. 5th then would be a huge (69%) reduction from 4th, only good for cruising (at legal speeds), as you'd be running 2 grand at 70mph, probably below your peak torque. Passing would be a kick, however. ::
I have a 0.5 sixth gear in my 69. I really like it on the highway but anything below 70 and the car does not want to pull it if you need power right away. The 5th gear on mine is 0.74 and is great below the 70 MPH mark. If you have a 1 to 1 in 4th and a 0.59 in fifth that might be to big of a jump for your liking.
Will you be able to use such a high gear? My 347 wih its wimpy cam doesn't like to live below 2000 or so RPM. With my .76 6th gear and 3.50 rear I do 72 mph @ 2500 rpm.
Also, consider going into and out of that gear. What would you have to be turning to be able to go into that gear with out bogging? How slow would you have to get to to go out of that gear back to 1:1.
The chart I posted is from a program I made when I was doing my 6 speed swap. I wanted to have printouts of the different tranny/rear end/tire combos so I could figure out what I wanted to go with. If you post your tire size, AOD gear ratios, and rear end ratios you are considering I would be happy to make you up some charts. Here are a couple AOD charts I made for someone else