Both Rockler and MLCS show listings for zero clearance inserts for old Craftsman saws. I Have the MLCS insert in my 30 year-old Craftsman 10" contractor saw. Another possibility is to make your own out of 1/4" Masonite. Use you old insert as a pattern.Agree on saw blades. I had been using a cheap Irwin 60-tooth blade, but switched to a Freud Avanti. Day/night difference. The Freud cuts faster, smoother and more accurately than the Irwin, and for not that much more money.
Bob