Factory KH 4-Piston Calipers

The Swinger had sat for about 10 years with lines removed. All the pistons were rusted in place. Too much hassle and expense to even attempt a repair. The SS upgrade looks wonderful, however, this is all in U.S. $ and it will cost me an initial 40% extra - plus shipping and taxes. Not affordable.
On the other hand, choice number two is to retain fully functional 9-inch drums and convert to P.B. Either way, I am still going to need new M.C. and play with the lines and fittings. I suspected that there were other (core/used) calipers out there. But, how much difference can I expect regarding 'pedal effort' - if changed to manual discs? Having said this, IF I decide (or am convinced) to go ahead with the discs, I need to start with fully functional (aka: rebuildable) cores - not having to 'sleeve' them. I only drive up to 3 K. miles per year and do annual fluid changes.
p.s. The car is going to outlast me. Thanks for interest.