Cylinder has spark but not firing..

Just because a cam WAS good when you put it in does not mean that it will not wipe out after it is installed. A flat tappet cam will wipe out MUCH faster with today's low zinc oils especially if you do not use an additive, break in oil, proper break in procedure, used/mismatched lifters.
Are you sure your carb is good? Jetted properly? Power valvegood? tuned right? A 750/790 as you say you have, is way too large for a stock 360. The pictures of your plugs, to me, show a rich condition. A points dist will not give a good strong spark like an electronic/HEI/MSD type ign.
You should take all your plugs out in the order that they are in the engine and take a picture of them, so we can read them. the reason I say this, I just had an engine with plugs that looked like yours on 4 cyls. #1,7,4,6. I pulled the carb apart and found the jet was larger on one side of the carb, which was giving the 4 cyls an overly rich cond.
You never mentioned anything about your carb tune. Fuel, air, spark