New tranny and now it lags

[betonj97]

So I was having some problems with my 700r4 slipping so i decided to pull it out and replace it with a TH350 that is freshly rebuilt, it has a 2500 stall converter as well. My problem now, is the lag i have coming out of first gear, I can't even do a brake stand (no burnouts). I replaced that kickdown cable thinking that might be affecting it and same thing, then i replaced the vaccum modulator even though that is ment for upshift, an still nothing. The only thing I can think of is that stall is to big and I am basically bogging of the line.
Any suggestions.....?

I have a 69 327 with camel hump heads, cam, etc.