2-1/2” bore size no ID tag help please Tecumseh rebuild help

So I picked this up it was on a bird mini bike. Adds say it came with a 3.5hp but there was a model with the 3hp. Head gasket is extremely smaller then the hs40 head gasket I compared it to. But it’s a slightly newer engine off an old Aries snow blower. Shaft is smaller diameter on the lil older Tecumseh to. Dunno if that matters. Nor size is 2-1/2” if anyone knows what piston rings parts number would be. And can I upgrade the valve springs and cam. Maybe off a different hp Tecumseh. Also the gov arm going in to the block seems sloppy is there a seal that firs bad?


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Uour ruler shows 2.5" bore or am I missing something?
correct sorry I was Measuring something else to when I took that picture and I must’ve got them backwards. Sorry about that probably should’ve double checked be for posting lol. I
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Thanks skip! You wouldn’t by chance know what the rings parts number is would you? Or how can I look the engine it self up to get a list of part’s numbers.