Lockup to non-lockup question(s)

4spdragtop said
So to sum up, if I understand correctly, with my 340 and crank register of 1.58"ish, I can use the early version of the lockup trans(which I have) as long as I'm using a lockup converter??
Another question....is my trans a 3 spd?
Thanks

No. To use a LU trans and LU converter your crank needs to have the 1.8 pocket. Which any 68 or newer V-8 or slant six should have.