727 puking out the front seal

I have a 360 backed up by a 727 with a 2800 stall in it. I have had two issues with the transmission.

First when it shifts from 2nd to drive it acts like it shifts to neutral for a second then goes into drive.

Then second problem just started happening. I put about 80 miles on the car since i completed it and all was good except the shifting issue then the other day when I had it idling it started dripping out the front pump seal. When I shut the car off it started pouring out the front. Now anytime I start it it just pours out the front. I have a locking dipstick in it and I was wondering if the transmission needs to ventilate or if pressure was building up in the transmission and blew out the front seal.

The transmission was rebuilt quite a few years ago had about 6000 miles put on then pulled out of the car and sat in the garage. I pulled it apart and put all new seals in it before i put it in the car. The band clearances looked good at the time.

I am in the middle of pulling the trans out now and ordered a B&M overhaul kit for it. I just don't want to put it all back together and blow out another front seal.