Can't help with the color issue, but the Minwax matte spar poly I used on my almost finish-less pre64, has held up very well for 10 years, at least. I thinned the first few coats (although some here have said that doesn't do anything) to help it penetrate and so as not to gunk up the checkering. Looks good and fixed the annoying POI changes I had to deal with annually.
