New D3 3J - Where to Source Piston Rings for Stuck Diesel?

Hello All -

Recently acquired a new to me D2 3J #4346.  Was sold as a good runner, but diesel engine was stuck.   It was supposedly "recently free".  Anyways, I pulled the head to inspect and found what appears to be dead and decayed mice and their droppings, urine etc in 2 of the cylinders.  The sleeves don't appear excessively worn, but the pistons are stuck from this mixture.  There was a lot of evidence in the head, and some of the mix must have gotten through the open valves down into the bore.

It is currently soaking in a 50/50 diesel/ATF bath.  Plan would be to fire the holes as well to expand the bores and then stick the head back on to retain the sleeves and roll it over.  Once free, I would pull the oil pan and pull the pistons out the bottom and re-ring them, then pull the head and hone the sleeves and reinstall the new piston/ring assemblies.  

Rings appear to be called out as:
5B907
6B2171
6B2133

Only 2171 shows as available through CAT parts.  Any leads on where to source an entire ring set for this D3400?

Any comments or concerns with the overall plan?  Am I asking for an impossible job to pull and install pistons in frame?  Any input is appreciated.

Thanks - Chris