Noob question 727 really low shift points

Just getting my project rolling. Engine is running, not strong but consistent (still needs good timing and tuning), while in drive going through the gears, 1st to 2nd and 2nd to 3rd are both done by between 25 and 30 MPH as I don't have a working tach, I'm not sure what RPM that is but its not much, I've been taking it easy on this thing because it hasn't been on the road in months and I'm babying it just to get a sense of what's what.

Background on the transmission, neutral safety switch had backed out and lost fluid. Shop filled it back up after reinstalling NSS and said drive it for a month, come back and we'll do a full service, drop the pan and check it again to see how it did. Here's a photo of the pan when they dropped it originally to inspect and refill it and suggested driving it for the month.

Some additional background on the car, front end of my baby was almost a full rebuild, steering column, plunge joint, pitman arm, idler arms, tie rods, ball joints, shocks and I'm doing control arm bushings this weekend. Transmission rebuild or swap is not something I really want to think about at the moment after what I've spent in the last month getting it up and running mostly safe down the road.

Never messed with transmissions at all, comfortable working on a bunch of things on the car but this is one area that has just been something I avoided. Anything I can check for as far as basics go, just to maybe eliminate some things?

Thanks in advance.

Fluid is red, no big chunks or black flakes and taking into account what a picture does to stuff like that I would say it looks fairly normal.
Stock these transmissions shifted really early, but some adjustments to the throttle pressure might help.
Has it been checked and set that you know of?