While the wire may be modern and not as original cloth covered, I thought that the Classic Parts 1940-46 Wiring Harness-Generator at $229.95 was a reasonable price for a replacement harness. It even includes wires to add signal lights. If you want a period correct reproduction you will pay considerably more.

1954 Chevy 1300 engine 235 (1959)
1955 (first series) Chevy 3100 engine 261 (1957)
1927 (other brand) Model T- engine 327 (1968)