Oh man, it's a twin Onan. for some reason I was thinking it was a Tecumseh single.
That looks like a nice tractor for it's age.
Deck has obviously been painted along with the rims.
The best part it's got a bowtie on the front
I am told the Rustoleum old Cat yellow is a close match to the original Sears mustard color if you want to spray bomb it.
If you want tri-ribs, you may have to find skinnier rims for the front if you go with the smaller 4.8-8 size. They make a 16x6.5 tri rib
I think, but man they are $$$$$$ IMO.