One wire?
You mean self-exciting, with single heavy cable, no excitor wire?
Why not fix the excitor circuit?
Here's use of a delco alternator as a replacement, but it needs an excitor wire in position "L" of the GM universal pigtail, rest of pigtail is blanked off with silicone, and the big heavy wire goes to the lug directly (2 wires, like original):
Here's another Delco Alternator Installed - Rennlist Discussion Forums