68 C10 Brake Help

[woody 68]

I've got a 68 C10 drums all round. I put all new parts hoses, springs, pads, and wheel cyclinders. I can bleed them and get a good firm pedal no bubbles from the bleeder then it sets overnight and the pedal goes almost to the floor. I pump it a few times and get an OK pedal. Bleed it again and get a good pedal. then the same thing after it sets overnight. Do I still have air in the lines and just need to keep bleeding or start looking for another problem? I never had a problem with the soft pedal till I replaced all of guts. I replaced because the pads and drums were worn out and just decided to do it all while i was in there.