[Dragncar]

The 4.25 stroke thing started out at Butler. You can offset grind a stock 455 crank .040 and down to BBC rod size. Butler was the first to do this with off the self 6.8 BBC rods. At least he told me he was the first guy to do it.
Then you have Butler with their deal at ROSS pistons, they are the ones who got us our own forgings, not a other brand adapted to a Pontiac. They have more off the self Pontiac pistons than anybody. And they sell more Pontiac E heads. Have had a relationship with Vic Edelbrock(RIP) for years.
So the answer is, Jim Butler.
Also, there was the era when you could not get any steel Pontiac aftermarket forgings. Thats why H-O Racing went with the BME aluminum on the street deal.
So off the shelf Chevy rod combos were a fix for a need. AND, longer rods used to be a thing when all we had was iron heads. Once you fully port a RAIV or D port head stuffing a longer rod got a tiny bit more power. But once we got aftermarket heads the point was moot.