[PGSigns]

OK less start from step one.
Does the distributor have 12 volts to the proper terminal ( I have seen the hei's with the power wire on the tach side) in both the start and run position?
Have you brought the #1 cylinder up to top dead center on the compression stroke and verified the alignment to the post on the distributor you are using for the #1 plug wire? Pull the plug and put your finger over the plug hole and slowly bump it over till it pumps air and then line up the timing mark.
Have you verified the firing order of 18436572 and that it is going in the right direction? As a reminder just bump the motor over to see what direction the rotor moves.
Have you looked to see if the engine is getting a squirt of fuel when you pump the throttle?
Is the fuel still any good?
Have you pulled the plugs (all 8) to see if you have flooded the engine while working on other things?
Does the engine have good compression?
If you go through this list of things and are all yes to the questions it should fire. You said you had spark so the process above should get you running.
Jimmy