4.8 to th350 troubleshooting

[Jstock85]

Got a couple quick questions for you guys out there.

First I swapped a 4.8 for a 305 and reused the 350 trans which ran fine with no issues. After the swap there seems to be some kind of delay when I push the accelerator. It will rev up then begin to move. Kind of like driving one of those go karts at a track. There is nothing electric on the trans so i'm assuming I need to change the converter. The new motor idles and runs fine.

Can anyone confirm the difference is the power band is my problem?

Also can anyone recommend a converter I should use or what stall speed I should used if the is in fact my issue?

Thanks
Jeff