I just found out that Sonnex has the pressure valve for the older transmissions. I thought it was only for the newer transmissions.
I haven't used the valve yet, but I like the design. It is to allow the fluid flow to cooler when in park, without the drain-back issue of just drilling the valve body.

I have been using the Trans-Go TF-2 shift kits, with their manual valve which seems to work good too.

When I re-located my vent, I drilled the main case when it was out of the car, but you could do the tail shaft extension too.
A Pneumatic 1/8" NPT to 1/4" push to connect tube connector, and some 1/4" Nylon Pneumatic tubing run to a higher location like the firewall worked good for me