turbo350 2nd-3rd slipping?

[cakneller]

I'm about to do a trans swap and would like to get a couple of more miles out of my turbo350 before the swap. The problem is 1st to 2nd shifts well, but 2nd to 3rd doesn't. If you have the power down it really shifts slowly.
slips like crazy;(
Is there a way to change this w/o taking out the trans? shift kit?