I have a ‘94 Merlin (not Extra Lite) and I don’t think it would accept a 28mm tire, especially in the rear. Different forks may afford more clearance in the front.
I also have an early Moots with a 1” head tube. It fits 28’s no problem. Moots are a bit more money than the other two, but definitely worth adding to your searches.

My friend’s Ultimate cracked at the dropout, so a place to check before you buy.