Transmission Shift Problems after HEI replacement

[conquistador]

Was hoping for some suggestions on how to start diagnosing this problem.

I recently purchased a 1966 C10 with a mildly built 355 and what I was told to be a turbo 250 transmission. The engine and transmission were put in the truck by someone else so I know little about it and with my added lack of overall knowledge, diagnosing problems is hard.

I took my 66 to the local tech school (buddy of mine runs the automotive dept) and he diagnosed the cutting out I was having as a bad HEI distributor. The kids did a great job replacing the HEI and installing the new radiator/electric fan but on the drive home I ran into a problem.

When shifting from first to second, the transmission will stall then surge, stall then surge, stall then the truck runs like a bat out of Hades again. Since it only has to gears it doesnt do it often, but I'm wondering with the new HEI if there is any adjustment to the transmission that needs to be done. The truck has gone from running average to running great but the transmission seems to be the issue now.

Any suggestions out there?