Bill:
The rear-end rebuild on the pickup was done in '85. I pulled a junkyard 3.73 w/Eaton posi 12-bolt off a '69 GMC stepside. It was short a driver's side 6 lug axle. I had to get a new one from the dealer, that ran about $85, I think I spent about 8 or 900 back then, with labor at Simmons garage in Tucson. The junkyard got my core open 12-bolt. I had another 12-bolt rebuilt for my '67 K/10 Suburban in '95. I spent about a grand including rebuild [seal, shims, etc] kit, new Moser axles, and new Auburn posi.
In the '68 C/10 pickup, I'm turning about 3000 RPMs @ 70 MPH.
Yes, one reason I chose the Edelbrock was the lower price than a Holley. $225 is about what I paid to Jeg's (or was it Summit?). [If Carter still made the AFBs it would be even cheaper -- but hey?] Another reason is I've had good luck in working on the AFB types myself, I don't have to find a Holley wizard to cast out its demons. I did need a good Carter /Edelbrock expert to help me set up my 1404. We changed out several sets of metering rods and different springs, until we got it running smooth and strong. Right now performance is good, although I'm getting 12.4 MPG. That may be as much silk as you can sew onto an old pig's ear.
I have an HEI on my V8 350 in the '71 Jimmy. It's not hard to find fresh replacement [and HiPo] components for the GM system. I think some things are common to HEI in V8s and L6s. Modules, coils, counterweights, springs-- I know I replaced the module and grommet several times until I found out it was really a fuel pump gripe, but that's another truck. You might have a local shop check out your HEI distributer and adjust the advance curve to your specific application. In Tucson, there is a shop, Automotive Recalibration, that specializes in that.
The fresh 292 is more fun to drive than a 6 year old crate V8.

I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.