Turbo 400 leaking/blowing ATF out the top of the dipstick tube

[WinDancer]

My turbo 400 transmission, after being hot and filled to the hot mark on the dipstick, is now blowing Tfluid out of the Dipstick tube. The o-ring had been changed twice with no change. It is not leaking anywhere else.

If I take out 2 quarts it stops the spewing and engages the way it should, but is off the bottom end of the dipstick. That's not gonna work for me.

The tranny worked just fine until filled to the mark.

I filled it with the amount of quarts it called for when we swapped it to replace the 350 and had it out for cleaning and painting- it worked very well until the mechanic on Tuesday filled it to the mark on the dipstick.

Did Chevy build turbo 400 dipsticks in different lengths?
Are the 400 short-shaft 400s using a different length?
4x4s maybe?

Any knowledgeable help is disparately needed.

Who do I call or where do I find info on dip stick lengths for the turbo 400s?

TIA,