Stock replacement parts will usually duplicate the performance and durability of the ignition parts originally available in 1981. They are a good choice when cost and fit are a desired combination and the engine does not have headers.
However, the idea that stock parts will always provide a level of performance enhancement matching the other aftermarket modifications on the engine along with good durability is not a valid premise.
The engine in question is modified with headers so, already, by making the stock ignition wire choice, you're taking a chance. The problem is that the spark plug wire and the spark plug boots on OE replacement ACDelco wire sets are not designed to be durable at the levels of heat an engine with headers will produce in areas around the spark plugs. This is why stock plug boots often get fried on engines with headers. I would never use OE replacement wires on a first gen Small Block V8 with headers because of that.
I always use MSD spark plug wires on engines with headers because the materials used in making the wire and boots is designed to be able to "survive" at the elevated temperatures typically seen in the space around spark plugs from engines with tube headers. Plus the design of the MSD wire from an electrical perspective is way better than the materials ACDelco's suppliers use.
On my 71 BB Coupe, which has an engine with headers, I have a set of MSD Super Conductor wires I installed in 1994. I remove the plug wires once every couple of years and measure their resistance and inspect the boots. Every time they test ok and look good so I put them right back on. An OE replacement Delco plug wire which duplicates that level of performance and durability is sooooooo not gonna happen.
Secondly, on any engine modified for improved performance, I never use OE replacement spark plugs. One reason is the heat range of a stock plug is almost always too hot for a modified engine...if that engine is ever going to be driven in a manner which will allow the user to enjoy the additional performance the modifications provide.
Additionally, OE replacement spark plugs are 40-year old technology as far as plug performance and durability. Is that what you want from your modified L81? I usually upgrade modified engines to some sort of aftermarket plug which has either platinum or iridium tips. You can get that in some of ACDelco's spark plug lines, ie: "Rapid Fire" and so forth. I, also, drop down at least one heat range in my plug selection.
For my own cars, I use nothing but Denso Iridium Power plugs. The Iridium Power design combines the best of Denso's OE spark plugs (which, in recent years, have been used in some GM vehicles, such as C6/C6 Corvettes) and Denso's racing spark plugs. Admittedly, Iridium Power plugs cost more but they have outstanding durability in high-performance engines. The one I'd recommend, for street use along with occasional drag racing or autocross, in an L81 would be the ITF20.
I agree! Unless you like a lot of bling . . . stick to stock! Everything else is just hype.
