What tomearm ?

If the OP cannot reassemble the arm or re-solder the wires I don't really  see how he is going to drill new holes in his plinth to install a Rega arm.  And that's assuming he wanted to in the first place. The Rega is not a drop in replacement, and as I said in my first response, the turntable would need surgery to accommodate it. It's not worth it and would look terrible, even if it could be done.

Sending the arm to a technician to reassemble is the most sensible option.

New Jersey is quite a ways from Mesa, AZ. Why not search for a more nearby dealer who would be kind enough to take on this job? I found this list of 10 places, not all of which are suitable but it’s a start, by doing a Firefox search:https://www.yelp.com/search?cflt=hifi&find_loc=Mesa%2C+AZ
Audio is a focal and local world.  One of the stores on this list may be able to recommend a repair person, even if they themselves cannot do the job.

Well I would rather send something like a tonearm across the country to a known high quality tech than take a chance on someone who may or may not know what they are doing. Working on tonearms is kind of like watch repair, very delicate mechanisms involved, not everyone can do a good job.
BillWojo

Enlarging a hole is a very easy proposition. Can be done with a carving knife. I seriously doubt the OP cares what it looks like. He would like to be able to play music immediately with a cheap solution. Do you understand what advance lung cancer means?

Also, we do not know if the old arm can be reassembled or if parts have to be ordered prolonging thing further. The safest thing to do is buy almost any used 9 " working arm and throw it on there.
Here is one, https://www.ebay.com/itm/154319851659?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&...

EVEN better a Project arm for $99!!  https://www.ebay.com/itm/Pro-ject-Carbon-Fiber-Turntable-Tonearm-Black-Project/353424393693?hash=ite...