I have a 50A from about the same vintage. I found a great buy on ebay
for Freud 15" Ultimate Cutoff blades. I bought 3 of them about 8
years ago and I am still on my first blade. I work with a lot of Ipe'
and Hard maple. The frued always gives me a glass smooth finish.
I've gotten lazy the last couple of years and don't usually change out
my blade when I cut PVC or other synthetic materials. The Freud is
almost as good of a blade as the 50A is a saw, it may even outlast the
saw (hahaha...)