Those are good compression numbers, have you checked that the little diaphragm under the breather cover isn't torn or sticking? We've had a few Kubotas (not a V2003 specifically) that would start dribbling oil out of the tiny weep hole and needed them replaced. Sometimes they get gummed up with engine condensation (coffee creamer) and will stick and let oil splash through. Pulled ones that looked fine, installed the new one and problem went away.
For a manometer, an old school Yellow Jacket dial type will do you fine (and not break the bank like the digital models). Looked real quick and the model I have is a 78060.
As far as a leak down; There are adapters and a gauge set you can buy for getting real numbers. But the quick and dirty way is an air compressor and a rubber tipped air nozzle. Pull glow plugs, either bar engine over to close valves on each cylinder or take off the valve cover and loosen all your rockers (which is actually faster and easier), and blow air in through the glow plug hole. With valves closed the air should stay put and blow back out when you pull the nozzle away. If you can hear air escaping through intake or exhaust, it's valves. If you hear it through the oil fill or radiator, it's (most likely) a head gasket issue.
