I'm in the middle of having a new base made for my YS pedestal. A machine shop has simply sleeved the lower tube, then welded a half-inch aluminum plate as the base, with countersunk holes for the SS bolts.
I haven't got it back from the shop yet, so no pictures just yet--but I've seen it, and it's a beautiful job that looks like it just came from the factory.
I think this is the most simple solution to the typical corroded base problem, and it retains the whole pedestal-binnacle-nav station as before--no surprises or unmatching bolt holes.
My cost is less that a used YS pedestal, which usually goes for $450 or more.