Assuming the brakes have been completely rebuilt and are functioning well, it could just be a case of not being used to "old car brakes". I haven't had a collector car for about 20 years, purchased my '51 on Ebay and took it for a spin. Pretty scary (though not as scary as a 1919 Chevy I once had with mechanical brakes). Impossible to lock the wheels except on gravel, needing a lot of pedal effort to stop.
Fast forward two weeks, I was then completely used to the car and the brakes seemed fine. I was so used to modern power disc brakes that non power drums seemed terrible. In actuality, the brakes are functioning as they should. Like any car with drums, you want to be careful about wet weather, when they can fade badly- but most of these cars are driven on sunny days, so not a real factor. Nowadays I can cruise down a long, steep hill in our town without any trepidation at all.
Fid, you make an interesting point- while the brake hoses on my car look fine, I don't think they are new like all the other parts. I'll consider replacing them. I'll also see if I can drive someone's identical car at Jackson to see if my brake effort is out of the ordinary.