So I picked up a 78 peugeot (A08 I think) that was rotting in a friends basement. I don't have tons of money to spend on it. So i used all the components already on the bike, minus new tubes and tires. The gearing that i was forced to go with by doing it this way is pretty high (52/16) I'm super out of shape and need to drop down I was thinking 42/16 or somewhere around there. I have looked for a new crankset but that seems to be hard due to the cranks being cottered.

Anyway I am trying to find a cheap fix. I am very new to all of this, and honestly all of the crazy prices for components is intimidating.

Thanks for the help in advance.

I guess that i should add if it is not apparent that I am going single speed with this bike.

Why not just use the smaller ring on the cottered cranks?

Your question will likely better be answered over in classic and vintage, BTW. I know dirtdrop converted a PA10 to fixed gear (another Peugeot model with a cottered crank) and used the original cottered crank on his conversion, to nice effect.

I've converted several UO8s, but I've always switched out the cranks to cotterless in the process. (I've also done PXs and PRs). However, dirtdrop has the practical experience in this case. Post this over on C&V, he'll prolly be glad to help.