Sounds like you have or have access to much better & newer machines, which is good, since you can gather that up for a big project,
So are you looking for a classic machine for just the old/kind of neat factor? or just the fact it'll do a good enough job in a pinch & don't want to buy another $40k skid steer to have one at each property?
Either way, as arse_ said, the front wheel drive machines, (HA, H25, HAH, etc) are pretty useless for digging, with a little talent you could get buy using one for cleanup/top scraping, or as mentioned, running into a pile & moving it around to different locations, (would beat the shit out of a wheel barrow & shovel for spreading out a gravel pile)
You mentioned lifting stuff, My little HA with forks will barely pick a 12-1500lb hay bail onto a low slung trailer, & it's pretty sketchy doing that, I From what I've seen the later HA & H25 will do a little more, maybe handle 1500lbs more comfortably,
Steer clear of the early HA (pre '51 or '52) they had a bucket trip mechanism rather than hydraulics for dumping the bucket, at least '53-up had hydraulics, then even later in the 50's-early 60's the reconfigured the arm/bucket tilt arrangement, at that time they also had "down pressure" which is useless on a front wheel drive machine,
Somewhere in the H25 lineup they switched to hydrostatic drive, not sure how you feel about that, but thought it was worth noting,
Next step in size would be an HAH, it would suffer the same pitfalls as the HA, with the exception if bigger rubber all the way around so they do get around better off the hard pack. Mine is still tricky trying to get a full bucket while scraping/digging, but it is a bit better that the little machine just cause is has a little more weight behind it,
I also think once I get a set of forks on this machine it will pick considerably more weight than the little one, maybe closer to 2k lbs,
The only other Hough machines I have experience with would be the next size up form the HAH, & that would be an HF, this is still a 2wd machine, front steer, rear wheel drive, I think this would be a much better machine for doing any dirt work, since you're not lifting the drive tires off the ground,
The down side is they are getting to be pretty good sized, (roughly 12,000 lbs) at this point a guy could just keep an eye out for an old back-ho, or 4wd machine.