While I agree that olympic gold is more desirable and prestigious than any fast time short of a world record (and Oly Gold vs WR is debatable imo), the point about there being a larger dose of chance for olympic gold is an important one. You have to be in amazing shape on a specific day that happens every 4 years, and avoid any mishaps during the race (getting tripped, boxed in) that have at least a little bit of chance involved. Your ability to win may also depend on the race playing out tactically in a way that favors your racing strength (e.g., if the 2016 olympics was a sub-330 race, Centro likely wouldn't have won). You also have to be fortunate enough that another athlete of equal or greater talent isn't in phenomenal shape (e.g., 2016 Centro doesn't beat 2021 Ingebrigtsen or 2004 El Guerrouj).
If you want to know how good a runner is at their absolute best, their PB is a better indicator of that than a race than happens every 4 years. Everyone has the chance to go after fast times every year of their career, with at least a handful of racing opportunities where a PB could happen each year. So if you've run the 3rd fastest 1500 ever, you've got a running achievement that only two other people have surpassed, despite decades of annual opportunities for people to do better (though I acknowledge that track and shoe improvements make comparisons across decades less clear).
I will say that someone's Olympic and World Champ performances on the whole is probably the best indicator of how greater a runner is, since that gives you a much larger sample size and everyone is gunning for those races each year. But it still isn't a standardized measure of absolute peak achievement like a PB is, which is what i think makes fast times exciting.
To answer the original question though, I'd say 3:27 low or faster pre-super super shoes is equal to Olympic gold. Nowadays it would probably take a world record.