No experience with swapping the guts out myself. I did order a bunch of shifter pods from that ebay seller recently though. They are a little clueless, I'd be inclined to think the no named shifter I linked to is actually an XT, has the right matte finish instead of the gloss of the LX.

If it was me I'd just order both the LX and the no named one, they are cheap enough and hopefully one works out or gives you enough parts to scavenge. Keeping vintage XT stuff running takes some parts hoarding these days.

Edit: Also couldn't hurt to post in the classic/vintage section, someone might have more specific knowledge of cross compatibility. Retrobike.co.uk is a good forum for that stuff as well, geared more towards mountain bikes and things at least 20 years old.