That base is in poor condition, as I'm sure you know. I would throw it away. However the mission here is to fix the engine.
Ensure that the crankpin ends up round. You need to measure it to a ten thousandth of an inch at frequent intervals, and don't linish the smallest parts. Also remember that round does not just mean the same diameter everywhere, it also means having a single center.
I think I'd re-use the original rings, but that is up to you of course. My efforts to re-use piston rings have not been uniformly successful. Remember to put the rings in the right way up - that is crucial. Incidentally, the supplier in Thailand I have used offers gasket kits that include the connecting rod. I can't access ebay at present or I'd give you a link.
