Best valve body 700r4

Define " best"
Shift kits do different things
How do you drive ; what do you want to do with the car?

Sorry when i posted here I forgot the word street. I just want firm positve shifts when they should happen. I have a 73 with 6.0 ls in it and right now it won't up shift out of second no matter how tight (seen 7000) manually or in DR. foot on the floor let up a little and it shifts push back down and back to second. Also hunts or slips highway speed and give it half throttel. just normal cruise and all is well. I feel it just needs some brain surgery.