How would you plug these radiator holes? We have at least one in just about every room. I'm wondering if I should just try to cut a plug and leave the hole as is, or if I should widen the hole with the next largest hole saw to get a cleaner fit.

Wondering how I can match the color too. I'm guessing these are oil poly that have yellowed over time. I tried wiping garnet shellac on some scrap, but it seems far to orange. Maybe I'll try half as many coats then an oil poly on top next.