Hi Joe-
David Little mentioned J Custom, who I also recommend. Gus mentions shipping, which will be a factor. #2 SC weighs about 300#/1000'. E1016 cams weigh about 1# each.
You might be able to find a local source in the Bay Area and save some freight.
As for welding cable, the answer is a resounding "no". It looks all big and butch, but it's pretty thin-skinned. Do a Goggle search to see how the jackets are made, and of what materials. At our local convention center, the stage electricians are not allowed to tap power if the tails or any of the feeder use welding cable or is otherwise non-compliant.
2005 NEC {520.53 portable switchboards, construction and feeders} 520.53(H)(1) refers to "extra-hard usage cords or cables." Type-approved constructions are listed in footnote #4 of Table 400.4 "4. Types G, G-GC, S, SC, SCE, SCT, SE, SEO, SEOO, SO, SOO, ST, STO, STOO, PPE, and W shall be permitted for use on theater stages,..." That list isn't conclusive, as there are a couple other types in Table 400.4 that are "extra-hard usage" but not commonly found in single conductor constructions.
Have fun, good luck.
Tim Mc