I assume you are talking about the Classic Update kit made by American Autowire (AAW); I know Mike (Musclerodz) is an AAW dealer, but I don't know if he sells other product lines as well.
Assuming we are talking about the Classic Update, it is arguably the best kit available for the guy who wants to re-wire front to rear, have wires generally where the factory put them, and connect the way the factory did. When I was researching mine, I looked at the very cheap, universal kits, the moderate supposedly
GM-specific Painless kits, and the Classic Update.
The Classic Update is about half the price of all new, plug and play factory replacement harnesses from either AAW (Factory-Fit) or M&H. I believe you can generally score the Classic Update kit for between $450 and $500 or so shipped, and it includes new factory GM style terminals for every connection. Okay, almost every connection... my 69 is a manual trans car, and the connector for the clutch safety switch is not in the kit. AAW offered to send me the connector and terminals free of charge, but I reused my OE pieces.
You can do a search here for "Classic Update", and read all the good feedback, including tons of posts by me; I am a passionate advocate of the update as the best quality, best value, best supported (AAW customer service is among the best I have encountered in 20 plus years in this hobby), most flexible (lots of choices for extra circuits) harness available today.
Musclerodz (Mike) is a good vendor, and stands behind sales as well. It's really hard to go wrong here (unless you choose a "painful" harness