I'd think that all the stuff underneath the car would be the same.
The plumbing from the master cylinder down to the proportioning valve would be where the changes would be since the master cylinder on a PB system would sit farther forward off the firewall.
My first car was a well used 71 dart with the 73 and up large brake pattern disc brakes and no power brake booster. That car stopped amazingly well without a power brake system. I would be half tempted to just leave the brake booster off and then add it later if you think you really need it.