School me on trans basics

gents, looking for some help with my 904.

I'm running a 3500 stall converter and manual 904 from hughes.
Now that it's nice and toasty in NC, I started to notice a slight vibration right at 2950-3100 rpm. I can ease right in/out of it while cruising under very light throttle.
I have been tinkering with the cruise timing (vacuum advance) on the Fitech, and at first thought I was throwing too much timing at it. Then she started leaking intermittenly, but only when it was pretty hot outside, and I had cruised on the highway 20+min. I've got 3.23 out back and that puts me right under 3k rpm when cruising. Ran her a few nights ago, and on the way home, the torque converter bolts started intermittenly contacting the dust cover. PO also installed a pair of tube/fin style coolers under the car, impressive. Fluid is still clear and doesn't smell burned, level was spot on, but it did have some aeration on the stick..

So I think what I have is a very warm and angry converter/trans.
Plan is to:
1. Install a TruCool M7B in front of the radiator
2. Install a cast deep sump pan with x2 bungs for drain and temp sender(any suggestions?)
3. re-gear to 4.10

any other suggestions on things I should be looking at?