The grooves are an attempt to make the best of a bad thing, but don't help much, if at all.

I ride a couple of bikes with old steel road frames, and would not hesitate to get another such bike. My bare minimum requirements are an adult sized frame and aluminum rims. Today, I would probably lean towards something with 700c rims for wider variety of tires, but 27" would not be a show stopper. Now, Peugeot is a French brand, and French bikes had some weird thread sizes, e.g., for the pedals. So far as I know, American, Japanese, and Taiwanese bikes all adhered to a common set of standards for which parts are readily available.

Of course component compatibility isn't so much of a problem if it looks like the components are all in good enough shape to last for however long you want to keep the bike.