318/8 Speed Swap
Just me personally, I think the a 2.71 rear gear is about the sweet spot for the 8HP70. This gives an overall first gear of 12.71:1. A 727 would need a 5:1 rear gear to match it. A regular 904 would need a 5.19 gear and a deep first 904 would need a 4.64 gear. Just for a comparison.
With a 25.8" tire this would put the motor at about 1550 rpm @ 65 and just over 2K @
85. That's maybe a little low for the rpm at 65, but 7th puts it at about 1925 rpm. I could see 8th being only somewhat useful depending on the roads in the area.
I wouldn't go any taller than that on the tire though. Anything taller is only going to lug the motor even more.
Mine is happyish at 1500 and 1600 golden 2000 but I think your right I would have to possibly go to 3.23 but was going to look at tremec calculator and ratios see what the that might be like on a 2.94. The 727 I hate great drag transmission but that's about it just chugs gas current configuration and still needs a 3.55 or at least 3.23. I either do something big like this or 6 speed as an hour drive I may have to stop and get fuel. Also the 727 is tired don't see it as well spent money.
I could see an 8HP70 with a 2.71 rear gear being a decent solution for you. It would accelerate harder than your current set by a lot, and while you might have to forgo 8th gear until you are on the major interstates, 7th would work great until then.
Hmm...interesting. I was just looking at what what the setup I spec'ed above would be like to drive around on the street. If I stick to the 2000 rpm minimum, 30 mph is 3rd gear, and 45 mph is 5th. Wouldn't even get into 1:1 (6th gear) until 55-60. I've only driven an 8A equipped Challenger a couple of times and never paid attention to what gear it was in, but I would bet it does something similar. Difference is, the G3 can be run at 1400 rpm so 30 mph in 5th works fine.
I wouldn't be surprised if 1600 at 30 mph is fine even if the motor is only "ok" at 1600 rpm on the freeway. That would put you in 4th and 1770 rpm @ 30 mph. So many variables, but I would bet it would work fine.
EDIT - I had the wrong speed for the 2k rpm in the combination at the top.
