I tried looking in the archives because I know it's been discussed before but nothing came up. Sberry has said he has done it frequently but other's may have experience with this as well. Line boring just isn't feasible at this time.

The top swing pivot on my backhoe has a badly wallowed out hole that needs to be repaired. I'm fairly certain I can weld the hole up. I was going to tack a washer on the bottom of the hole to help make a shelf for the weld build up. This would also make it easier to get the weld right to the bottom of the hole without burning the bottom edge off. The bushing is 2 inches thick. What I need help with is the following:

Do I need to enlarge the hole prior to welding so I am not cutting into the Heat Affected Zone or is it OK to just weld the hole as is?

How much smaller diameter does the weld have to be in relation to the hole saw?

Being 2" thick I realize I will need at least 1 relief hole to remove the chips from the hole saw. Is 1 hole enough or is 2 or more better and what size should the hole(s) be? Is 1/4" enough. I'd have to put enough weld to be wider than the drill bit.

I plan to tack a plate at least 3/8" thick with a hole the same size as the hole saw to use as a guide for the hole saw. Could the hole possibly be done with a hand held drill? Should the guide plate be as thick as possible?
I have a big drill press that I think will fit the space but it would be quite tricky to align and square everything, especially being on a gravel floor. I'd have to move the drill press with the skid steer and then wrestle it into position on some plywood or boards. If the drill press would do a superior job then maybe it's worth all the trouble to set it up???

The hole needs to be 3". Will a 3" hole saw leave an accurate hole within about .005"?
I read about someone sanding the outside teeth of a hole saw down to have a slightly smaller hole that could be finished with a flap disc. Would this cause the hole saw to not cut as easy?

I need to do this repair on a really tight budget as I'm still waiting to hear if I will be approved for early disability. I have no other income and could never work a full time job. I can do about an hour at a time and that's pushing it. My back aches badly and I have very little energy. If I have to kneel down, I can barely get back up. It will take me quite a bit of time but that's OK as long as I can get the hole repaired satisfactory enough to fit the hardened bushing that goes in it. It's a shrink fit so I might need to get some dry ice to freeze the bushing prior to installing it. That brings up another question, has anyone used an aerosol computer duster upside down to freeze parts for fitment?

Thanks in advance