Great find !!
Looking forward to seeing it restored. What are the plans with the components ?
I'm not realy into GT, but I think I would look for Suntour components 'cause in those days ('91) Suntour was top of the line, though I don't know if GT switched over to Shimano by that time...
I also ordered from https://suspensionforkparts.net/eshop/index.php?_a=viewProd&productId=94
It took about one and a half week to get the parts home at an OK shipping price and nice communication.
I'm riding a Manitou 3 with the new elastomers. I tried with springs from Wings, but they didn't seem to fit. I realy had to compress the springs to get them inside, though I don't know how that works with a Manitou 1.
I don't know if there was an upgreat set from Englund for the Manitou 1, but I build in a cartridge damper on my Manitou 3 and it makes the fork far better with the rebound damper. Not as springy as it was anymore. Maybe you should check for such an upgrade if you're realy planning to ride the thing, though these are realy hard to find...
..now I read back this response, I see I used a lot of 'I don't know' in it, but I reckon that some other chaps on this site can confirm things..
hope you keep us updated with the built