'68 Impala Brakes

Hi - I just purchased a restored '68 Impala Wagon, 327 auto. The car has disc brake conversion on the front. I noticed the brake pedal is firm, but really needs a heavy foot before you feel the brakes working. Pedal is not spongy so it doesn't seem like a bleeding problem and it has a brand new power brake booster. Any ideas what I should at to have the right pedal feel?

I too, have a impala wgon . It came with manual drums all the way around. Talk about hard to stop. These cars are big.  I converted it to power with discs in front. Pedal doesn't move very far to stop. I would check vaccum connections and then bleed system to see if fluid flows freely.