LS TH400 help please

[72GreenMonster]

1. Current stock 402 400 trans. What is the stock stall and do i need to upgrade torque converter? If so which converter would i buy or is a matching bolt tc compatible with the older trans or tail the same? Not an expert here so any advice helps. Going to 02 5.3 with dished fp. Can i avoid drilling out the flexplate to match my th400 converter? If i buy a newer tc? Thank s

2. Which vss adapter works best and what needs to be done to pcm for that?

3. Engine mount position keeping the stock trans? 72 2500. Does anyone kno w the exact location on the frame and mount for this setup? Need c20 th400 help. Thanks for the help

Getting ready for machine shop and will share build soon.