Well, I removed the Toro's carburetor today. Disassembled, it looked okay interior wise. Just a drop of varnish in the bottom of the float bowl. Plastic parts looked a bit yellowed from five years of gas passing through it. The inlet needle looked a bit worn, but a carburetor kit will have a new one as well as new springs, gaskets, and instructions.
Contacted a local lawn mower dealer by email concerning the Nikki carburetor but haven't heard anything back, so I'll call them tomorrow afternoon and ask them to check their email. Need the Toro up and running by the middle of February. If it's not, I'll rent a small tractor and mow my farm. It won't need cutting again till late March or early April anyway. After that, it will need mowing every three weeks to stay ahead of the broomstraw and briers.
I've got three major projects going on right now... Mom, the Nano camper, and the Toro get the miss out of there. The chainsaws only needed a good cleaning and their H and L fuel settings tweaked a bit. Got a 1996 Homelite chainsaw (16") I'm thinking of tearing down and rebuilding, too. Got to find the fuel cap with bulb first at a very reasonable price. Homelites are easy to rebuild.
If push comes to shove, I might have to do a top end valve job on the Toro. The intake valve might be gunked up or needs a good polishing. They get sooted up sometimes from years of use of this Ethanol 85 Octane crap gas. I'd need a gasket kit for that, too. If the valves are not seating correctly, I lose compression and extra air is sucked in and leans out the fuel mixture. Might cause a backfire through the intake if the fuel mix is a bit rich or the timing is off.