That torque converter range is just what you need. Lol, that rear gear change will be a lot harder than getting the correct speedometer gears installed. Give the Fluidampr #720201 some thought if you aren't running one - they really do make a difference. Engine vibration is usually what you hear most at higher RPMs. Also, a bolt-on transmission tailshaft vibration damper might be of help. I can't recall well now, but I do think some of the AOD tailshaft housings had lower flanges that were drilled for them. They are a simple bolt-on.