I was hoping that MtView Ranch would reply to this, just so I could see some more pics of his dozers. I have a similar Case 310 and have had for several years. I paid $5300 for mine and have had to put in a few dollars, but nothing more than what's routine for a 40 - 45 year old machine. Mine is a gear drive, which might be preferable for an older machine (maybe - I don't know). I love operating a powershift dozer, but I also love using my small, paid for, gear drive dozer.
I would lean towards a small Case 310/350/450 as parts, support, and knowledge are plentiful, or a Komatsu D20/21 (I think 20 is gear/21 is powershift) or a Mitsubishi BDG2 (I'm not sure if I've got all the numbers right on that one), but those are the ones I looked at, so of course they would be my preference.
Yes, dozers can be money pits, but you can greatly minimize that chance if you work on it yourself. Anything that has to be done to mine will be have to be done by me, but I accept that as part and parcel of owning a dozer. I had thought I was going to sell this one when I was "done", but know I've realized I'm never going to be done.
Good luck with your search and take care.