The problem is going to be if you have a bearing go in the rear, and chew up a final drive. I would think even finding a well worn used final, would be difficult.
I'm sure the bushings and pins and such are well worn in the blade, but so what? it would likely last for what you want to do. A look at the pins in the tracks, would tell you if there's enough left of the undercarriage that you wouldn't walk the tracks off every time you turn.
My uncle had a old cable dozer when I was a kid, he always said it was a workout for your arm running winch up and down. Just replace the cable before it breaks.
If you just want to run one to destruction to get done what you need, it isn't a big investment. If you want to fix everything that goes wrong, you would be far better served with a cat simply for parts availability.
I think if I was wanting to clear your property and the other things you want to do, I would be much more interested in a track loader than a dozer. I think a track loader would be so much better for pushing brush, digging your earth home, loading and unloading thing/ lifting service.
If I was living in the middle of nowhere, and wanted to be able to take care of my own property, I'd be looking for one of the old Deere track loaders with a rear mounted backhoe. It wouldn't do everything as well/fast as a dedicated excavator/dozer/backhoe/CTL, but there's not much of that kind of work, that you couldn't get done with it. Even better if it had a 4 in 1 up front. Dig water lines, push dirt, make your roads. Do it all with one piece of equipment.