these are the reasons people say "run premix" and "disconnect oil injector"
because there's just so many little things that could go wrong, and they're so catastrophic when they do.
Seems like you got lucky, it'll probably continue running, you could reconnect the injector or drain it and run pre-mix gas (advisable)
there will likely be less power now that you've probably scored it up a bit, lowering compression, but might still be usably OK
don't SAND anything, you can use a brake hone on the inside of the cylinder, you can sand grooves off the piston, you can cut/scrape melted metal out of the ringland too and make sure the rings seat snug but can also move/not get stuck.
getting a kit, do some research. the stockoshocko and 77 cast iron kits are more work and crappy and nearly worthless. DR is the best all around value, performance and reliability. you don't need a new carb, you definitely will want a pipe, and you DO need to upjet.