Project Make Casey Great Again achieves its first milestone: we have (compression) ignition! Plus the bucket hydraulics work, which is a nice bonus.
TL;DR version - rebuilt starter and new fuel filters. Long version - similar but with more false starts, blood, and swearing.
Downside is he doesn’t want to actually move - no hint of either forwards or backwards action. Hopefully that’s just fluid: the transmission and power shuttle reservoirs were both full when I first checked, but now I’ve run the engine for a while they’re both off the bottom of the dipstick. No fluid pissing all over the ground, but the belly is black and sticky so I suspect he’s been dripping it away over the years he’s been parked.