i like two chainwheels in the 42/52t size on my bikes. it allows simple shifting, looks good and offers familiarity. this chainring/gearing decision will drive your purchasing choice. concerning look and composition, id take a look at the miyata catalog for that year and buy something that fits the look of the frame and derailleurs. if they're shimano, go with a light aluminum japanese crank (shimano or sugino) of that vintage.

i wouldn't spend more than $50 on the arms and $100 total for a used set (or used with nos rings). you can sometimes go real cheap (less than $50 for everything) and do a little cleaning/polishing with oven off and auto quality sandpaper. use a metal file between chainring teeth to renew them.

often, if you like the look of your components, it rubs off in the way you ride and care for your bike.

i very seldom use my brake adjusters to move the pad to/from the rim. they so seldom need adjusting, and it's easy to untighten the cable anchor and readjust cable length. if adjusting cable length continues to be a problem, you may try completely removing the calipers and overhauling them.