4 speed help please

[Kjames]

I have a 70 chevelle with a Borg Warner t-10 in it, I just had a 10.5 Hayes clutch installed in it but I had carb problems so it could not be properly tested, the problem is it feels like I'm starting out in 4th gear and have to give it a lot of throttle to keep it from stalling, the play in the peddle is exactly where it should be . Any suggestions on what is going on