I have 500s on my Raleigh Flyer. Its a 80s racer, has the smoother looking calipers. But the weimman pads are terrible. I ride with the brakes adjusted up. But not much happens when the levers pulled. Got 700c alloys on the bike.
Thinking of fitting some pads I got from a crummy kids bike. Is bound to stop ok then
It largely depends on the rims, but the horrible cheap un-machined shiny rims common on budget racers from the eighties don't brake well with any pad material. When wet they don't brake at all.
The best pads I ever had on my Raleigh Criterium 12 were some very cheap Raleigh branded blocks from ebay. I've also found some grey fibrax ones that worked well on these rims.