"...Double roller chain & gears is a must in a Pontiac..."
That's just one man's opinion.
I disagree. I tried one DR set. After I discovered that the chain stretched just as quick as a stock type chain, I went back to stock type sets, in TRW boxes. Don't know who made 'em. Never had any problems with 'em street or strip. I always kept some extra chains & swapped 'em out any time I had the timing cover off. They were dirt cheap back then. Nowadays, a stock type Cloyes set is almost as cheap as just the chain.
https://www.rockauto.com/en/parts/cl...iming+set,5756
https://www.oreillyauto.com/detail/b...c3007k/2625477
I think I remember Cliff saying that he uses the Melling stock type replacement set, even in his race engines.
https://www.rockauto.com/en/parts/me...iming+set,5756
https://www.ebay.com/p/Engine-Timing...-350S/75561005