Case 580 Forklift

I am working on this machine for a farmer that bought it not too long ago and am running into a few problems that thought someone on here might know a lot more about than me. It runs and drives seemingly ok but i havent run it that much yet. Mostly trying to get the mast cylinder sorted out first. It showed up with the cylinder's threaded cap unscrewed and the brass spacer both sticking up out of the bore and obviously dumped fluid if you tried to lift the rod. The cap and spacer were pretty stuck on the rod and it turned out the top 1 or 2 inches of the rod was out of round and they had been squeezed on. And that leads to problem number one which is the cap is totally trashed, whatever was used to unthread before it got to us ripped part of it that holds the wiper, the threads are seriously messed up and it also seems somewhat out of round. So we are trying to replace that, I had no luck finding any thing online that even looked close and at the time seemed impractical to fix the existing piece so it was sent to a local machine shop that the farmer has had good luck with in the past who made a new one out of aluminun, but it came back and did not fit. It would start in but jam within a couple threads, i put some paint marker on it and put it in to try and guage what was happening and then i went down the machine shop my self to see if we could figure out what wasnt working and somewhat suprsingly was told they "thought they made the thread metric" but it was pretty unclear if they did that or not and then i was told to leave the parts and theyd see what they could do. It came back again with the leading threads turned down and then it screwed in another thread or so before jamming up same as before. Id assumed the original was 10 tpi threading but 25mm is real close and i cant really tell the difference on my thread guage from the old or new. so one of my questions is if its at all possible that a cylinder like this one would have metric threads on it? The rod, bore, and fittings are SAE. And other question is does it seem possible to source a premade replacement anywere and if so where might i start calling. The machinist is maybe coming out to look at the machine this week so maybe he can figure out whats going on but id like to start thinking of alternatives if that doesnt work out. And i guess another question is if its not possible or practical, and if the threads of the old one could be cleaned up enough to get it to fit would the lack of good threads be an issue with it failing under load? That would still leave the wiper issue but that could maybe figured out i guess. And onto another question, my original plan was to pull the rod all the way out but as far as i can tell it is stopped by a shoulder on the welded in top piece, so the internal threads look ok but i cant really access them to measure or inspect very well, and so i guess im trying to make sure that that is correct and there isnt any way to remove the rod without cutting the cylinder open? And also some of the pins holding the chain to the adjustable anchors are bent and id like to replace them and want to make sure i get the right kind, im assuming they arent just mild steel clevis pins but am not certain. I found the entire link as a CNH part (two pins and the plates) but that lists for 200 something dollars and i feel like there has to be a suitable replacement. Ive also found other forklift chain anchor pins but so far they are all listed by model and dont give dimension. So i guess im wondering if anyone would happen to know what would fit or what a suitable material would be to look for for replacements. They look to be a standard 5/16" (0.312") diameter pin. Im probably forgetting some stuff but hopefully this is enough information for someone on here to point me in the right direction on some of this. Oh and I did find seals for the cylinder and went with a vee packing set from hercules. When i first got the cap off i found what looked like a pretty new u seal that seems to match with a CNH part number for a sealkit that supersedes the veepacking for this machine but im not totally sure about that and tought the veepacking might do better with an old rod. And also if anyone has any generally useful information about these machines id appreciate that as well