Anyways..
without the partnumber and or detailed pics of the engine and it's ionternals (to know what crankshaft bearing(s) is(are) installed) we cannot positively ID that engine
we can only point you in the general direction
if that engine is 29cm tall (base to top of head bolts)
it's more than likely a 5horse (unlikely but still possible a 4 horse)
if it's smaller it'll be a 3horse and if significantly bigger an 8horse.
A rusted off aux shaft isn't exactly a sign for a decent engine state.
And not really encouraging either when we had to judge it's internals from that.
cracking the ehad open isn't a bad idea, then you can measure the bore and stroke to determine it's combustion volume (and thus the hp rating it had)
Someone painted that engine over (very badly) and that alone makes me think,
that someone didn't cared the slightest about if that engine runs or not...
which to me sounds like an already worn out and worthless engine.
the alternative would be that this someone is/was a moron;
which I can't rule out, but I think is a little less likely.
Maybe it was rebuilt like Wes sugegsted..
but then, why not fix the camshaft?
why put effort in rebuilding and ZERO in repainting?
Chances are it's not even that...
And if it would've been rebuilt after being repainted you'd see toolmarks and cracked paint all over.
Anyways.. you want to call it new for some unknown reason,
feel free..
just do not try to sell it as such, since that would certainly classify as fraudulent
I personally would suggest you to inspect it thoroughly,
before you try to start it up, rather be safe than sorry.
'sid