Very first thing to do is "catch it" when it's hot, and rig a multimeter to the battery, then crank it by jumpering the starter relay. That will leave the ignition "off." You want to see at least 10V at the battery when cranking.
If that is OK, try to access the MSD "big red" which is the main power, and should be connected "hot" all the time. See what that is when cranking
Another thing is to "rig" a spark tester and see what you have for spark........
This also could be fuel problem..............
