not many low/mid end motors have more then 3HP from what iv'e seen, and in the size area we're talking about, most 4 strokes are like 2-2.5 HP from what iv'e seen, thing is that from what iv'e read even though the 4 strokes have less HP, it has more torque and thus more hill climbing power.
the 66cc 2 strokes generally have plenty of power for hills though, cost less and mount in frame better.
thatsdax.com sells some pretty nice 4 stroke kits from what iv'e read here though.
your specs are a bit too precise for me though but before you make any purchases i suggest you read this thread: http://motorbicycling.com/f17/real-d...law-15268.html
don't want to buy an over powered motor get stopped and have no chance to register it under CA's set of laws now do you?