Or get a good machine shop to machine the whole thing out of a billet of steel. I think you would probably spend more trying to get a fabrication made and machined than just machining a solid steel part.
Russell has a good point. They are doing some amazing work these days with the CNC technology. Like, 3-D porting of cylinder heads from seat to flange. Find an Industrial Injection Service (SLC) video on that.
I would expect that a one-off custom CNC cut would be prohibitive, because you'd have to sink all the CAD and setup costs in that one part. How many billable hours is that? [My son does a fair bit of CAD, making custom bracket plans for the water-cut shop.]
If I was RK, I'd hang loose and watch for an equipment auction to come up with an L185 parts-lot FS.
I swear there was such a lot FS a few years ago at Wolgemuth's, because I looked at it long and hard. I think it had a cracked trans case (from ice), but was otherwise all there. Somebody had tried to split it, and gave up. It had no-saled at 3 prior auctions. Ended up selling for scrap price....
Run a Wanted ad in your area. Free in Lancaster Farming weekly.
Do you know where your tractor was sold new? If that dealer is still around (unlikely), they might know who else bought L185s in the area...You just might find another derelict nearby. Your tractor's twin?
Do old Kubotas ever die?
-P