I don't know for sure how your Massey is set up,
it is common for the filter to be on the suction line going to the hydraulic pump,
some pumps will have two sections some just one, usually the suction will go in the bottom of the pump,
remove the line leaving the pump and going to your loader valve, use your shop vac to pull on that line till you get oil,
once you have oil drawn thru the pump place that line in a bucket, then tie that line down securely and start your tractor,
once it starts you should have good flow, shut down and reconnect, top of the hydraulics to make up for what gets spilled.
I would not run the engine till I had pulled oil thru the pump those pumps do not like being run dry very long.