Matthew, welcome to Automotive Forums.. i had the 73 S3 Laguna myself.. but electrical is the worst thing to work on; old or new vehicles.. but in Fontana, you are in the heart of SoCal racing and modding; so their are plenty of people to help out..
Bolger Brothers and Vintage Coach are in your neck of woods.. and you do not have to necessarily even take it to their shop.. many techs do side work, as they get to keep the cash; instead of the company.. shop around; Rotolo Chevrolet might have an L1/L2 line tech that would way rather work on a car with 45 miles less of electric and vacuum lines, and no OBDII-- just air, fuel, spark..
also, when i was shortly stationed in the central coast, Fontana had a classic/muscle car show every friday from like april to october.. gotta be some classic car wrenchers walkin around.. and out at the Fontana Dragway, Super Chevy always does a few weekends in between may and august (they usually hit you guys twice, Bandimere Speedway in colo. only sees them once in aug/sept; just before snow)..
all of that said, you also have a WAY better tool than the olden days: the net.. google images, pinterest, super chevy online all might have schematics for you.. and if you find a library, or an old used book store with an old chilton's or haynes (not the newer ones); they had schematics in them..
classiccarwiring.com has color ones for under twenty bucks..
i could email you mine from my laguna, if you want; it is probably pretty close to your coupe classic, but it is black and white..
hope this helps, and hope you get it going this summer..