198 Trouble Starting

On a motor that has been sitting go ahead and take the spark plugs out and let the starter get some oil to the top.
Just 15 seconds at a time so you don't get the starter hot.
Is it a hydraulic lifter motor?
Go ahead and take the valve cover off and watch the rockers and make sure you don't have a problem with a rocker not moving.
And remember to enjoy the time you get to spend with your duster.
I am a old school shade tree guy so maybe a good tec can jump in here and help. Have you got the timing set?
keep the spark plugs clean and set your points or air gap if it is electronic.
If you have been putting gas down it very much I would just pick up a new set and give them a try. Hang in there you will get it.
Just be careful with the gas and sparks OK!!

And yes a bad vacuum leak will hurt it from starting up.
Get a new gasket and new plugs, Gas fouled plugs will not fire up.