TKX performance improvements?

So I had a 340, 727, 4.30 gears, 275-60-15 tires and a crappy converter it ran 12.4@106 in the quarter at 4200' air is always 6K+ during the summer here. I hurt the engine racing a mustang a half mile, I won but lost a rod bearing. Engine knock and no legs to run down the highway had me bummed, so I did the logical thing and built a stroker and put in a TKO. It is a Keisler engineering machined TKO trans to fit without much trimming, it did but didn't. The TKX is way better in all the right ways, and that's what I'll go with when it breaks. I just recently trimmed the floor and upper crossmember for more clearance so it had more room and can be changed easily for when I break it out in America somewhere.
On the performance side with the 422 3.23 gears and 275-60-15m it ran 12.4 at 116 -118 mph 1.99 60' BUT I could drive to the track 65 miles at any speed I wanted comfortably and not get passed by minivans and Yugos. I had swapped the 4.30s to 3.90 I didn't have 3.55s so I used the 3.23s which I'm happy with. The 3.90s were worthless too much multiplication and no traction, the 1-2 shift was also super early and would break traction badly in second. Now with a 340 I'm thinking 3.55 3.73 would be the ticket as my 340 was happy to 7000K but my 422 got lazy around 5600 5800rpm but the torque difference is significant. The TKO OD trans is the best thing I've ever done to my car period. I did opt for an aluminum flywheel on the 422 and a small clutch for light weight and it's great until you want to just lug out of a drive through. With the upper 240 and lower 250 106 duration cam single plane intake it can be slightly surgy but it's worth it IMO as it just feels so snappy and responsive everywhere. If you have less cam or don't mind it being a little rowdy at idle in gear I highly recommend the aluminum flywheel and a lightweight clutch. Now the gearing of the trans is very important as that should take advantage of your engine specs, rear gear and what your driving conditions are as well as your rear tire size for highway driving. With 3.23 and the .068 OD and 275-60-15 at 75 I was 1700 1800 rpm and your 340 might be lacking torque below 2k to enjoy that but mildly camed dual plane 340 might be fine. Lean on the product manufacturer to help you choose the right ratios for your needs and wants. Good luck and happy shifting.