Looking for 2 upper fork tubes in original finish in good condition or a single one if thats what you have
Aprilia ones can be modified to work. My son had a set done for his race bike a few years back. Unfortunately, I can't remember who carried out the work, although a quick search does not bring up any familiar names, they may now be defunct. A specialist suspension shop should be able to guide you in the right direction though.
I have a single ST2 outer tube hanging around, but I'm not sure if it's the same. If you think it is then I'll dig it out and see what state it's in. I know it's at the better end of the scale, but might not be perfect.
They sometimes come up on eBay … I got some recently quite cheap because they were damaged but the tubes were good which was all I needed … Spotted these today https://www.ebay.co.uk/itm/1998-98-...2349624.m46890.l49286&mkrid=710-127635-2958-0
They don't seem to have corrosion but shame about the top of one of them, just checked my 748 and that top would show a lot, wouldn't be to bad if it was at the bottom as i could turn the fork around.
Looking at the ebay listing the ST one I have is different, 50/54 Yokes, not equal as the ones shown. Sorry I couldn't help.