Rough idle turned to crank then ka-thunk

Alright sounds like it'll be easy to do


No problem, and now I should add that;
1) If the cylinders are devoid of oil, and the throttle is closed during cranking, then the engine will not be able to "suck in" hardly any air at all, and if air is not going thru the venturi, then neither will fuel be.
2) in order for the engine to burn fuel, it has to first be atomized, and there has to be a percentage of it existing as a vapor, to even get it started. Therefore, a fuel that has laid on the plenum floor, for any length of time, all the volatile compounds have boiled into the atmosphere, and the heavy gas left over, while being combustible, is not at all eager to start on fire, even with heat of compression, if you have any, added in.
Once again; I cannot say if this is your problem, but a compression test will prove the concept.