I have a reasonably old specialized road bike with a cane creek aheadset that’s very grumbly so I’ve dismantled it and it has caged bearings not the cartridge type I’m familiar with.

The one’s I’ve found that look correct are 5/32″ -is that a standard or is there a variety out there?

They will be Imperial and that sounds right

Get a caliper on one of the balls, order them up loose. They don’t need to be in a cage, just blob them into the grease.