Well were to start stock 74 got me mad no power so i dropped in a 426hp 383(gmpp crate) and still my wifes bone stock 84 could take me (2:73 rear in mine performance axel in her's 3:07??)!!! So i looked around and a buddy had a 4:56 rear out of his 69 he said he would take $100 for it and me like an idiot said hell ya...Well i have this new rear end which is kinda great on the car but speedo is WAYYY OFF(i knew this would happen and was prepared for it) and car seems to run out of power LITERALLY at 4000rpm could this be because i used the dual point distributer? using a weinand stealth intake with holley 800 dominator. and what i assume is 50 - 55 (speedo is saying like 85)mph she is screaming at 3500+ rpm. If i got a 700r4 would it make a noticeable difference. I finally got the launch i want though i have to say the 84 hangs good. this is my 4th vette and im a certified addict and have come to the conclusion i will probably never be happy but the journey is so damn fun...............

 

A very good solution to your problem would be a 2004R tranny by Bowtie Overdrives. It can be built to hold your horsepower,even more! It will fit in place of the stock TH350,with only nut and bolt mods to the tranny mount,they will install the speedo gear you need to match your rear gearing and the cable will hook up with no mods. There is a mod to the stock shifter to accommodate the additional gear. As far as I know this is the very best tranny change that can be done to a C3 without some extensive mods. The gear splits are spaced more favorably than in the 700R4. A Tremec or similar 6 speed might have some advantages in some areas but will be MUCH more expensive and the installation will be more difficult. My $.02
Ron
ps: missed the TH400,might have to change the driveline.