ha... holding the gears manually to any RPM would and will be corrected with a transgo shift kit... kit should say that it will hold any gear to any RPM. its all in the valve body, also you dont need to use a vette valve body to get full WOT 4th gear shifts... its just the 3-4 upshift valve/kickdown valve that needs to be replaced... there are a couple companies that sell them and you can modify the stocker to do it as well.
you dont really want a 4th gear WOT shift... the 4 gear packs are weak unless you upgrade the stock 6 clutches to like 9. going from 6 to 9 will give u 30% more holding power in 4th gear. 4th gear is just a cruizing gear, but u can use to for HIGH speed driving, my B&M kickdown valve will hold 4th gear to 2/3 throttle, stock is like 50%, which means i can cruize at higher speeds without the trans downshifting on me.
heres a transgo shift kit... pretty sure it will hold any gear to any RPM. and it has the vette servo which is necessary to increase shift firmness and trans life/power handling. give DANA a call and ask him to be sure... his kits are awsome and he knows his stuff. I rebuilt mine with his prostreet upgrade with transgo shift kit etc.
https://www.700r4l60e.com/store/prod...&cat=65&page=1
heres a heavyduty rebuild kit for an 86 700r4
https://www.700r4l60e.com/store/prod...&cat=19&page=1
and a street strip kit
https://www.700r4l60e.com/store/prod...&cat=19&page=1
they aready have the transgo shift kits in them
