Kanter is the most expensive, BCCP also sells a front disc with 5 lug conversion, and I think Scarebird can guide you too if you want to go the put-it-together-yourself route.
Rear axles, call Moser Engineering of Moser Axles. You send them your axle and they make up a copy with 5 lug/as you specify. Not cheap but Moser are good axles, I think they are around $700 for a set. Didn’t check with anyone else
Talked to a couple of machine shops here and they refused to weld up the existing and redrill . One reason given was the multiple large access holes in the flange and that the axles are hardened and will not perform up to spec if welded. Have heard of people doing it though.
I stuck with 4 lug on my car. Lots of new wheels either steel or alum available-American Racing, Wheel Vintiques.