91 cherokee with a motor swap in it. Got it how it sits dropped the oil pan and rebuilt the oil pump since it had 0 oil pressure. That's fixed now. There was major sludge in the block...got it started last night had a slight knock nothing bad sounding and it went away with throttle. However it smells heavily of gas and it sounds like its timing out a knock. Today went to start it and it won't fire...

 

Pull a plug and check for spark is always job #1. Keep the plug wire attached to the pulled plug, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. You're looking for a strong, blue, snapping spark. Yellow/orange/white indicates a "weak" spark, which may not be strong enough to start the engine. Ignition coil is suspect if you have a weak spark.