On my '38 Raleigh, I fabricated home-made brake cables precisely because I did not trust the ancient cables, and wanted to keep the original calipers.
A (big enough) crimping tool (below) is an expense - but the 1/16" Campbell cable stops are cheap (~$1.24/package at Lowes).
I used the crimped-on stops in combination with the cable adjusters from a scrapped Simplex Prestige DT shifter.
I have confidence in my work, but Oldroads' recommendation to replace the calipers with more modern ones is probably the best/more conservative tack.