[cadillac_al]

If you really want to start at square one, you should do a compression check. Then check your timing tab/balancer marks. It does kinda sound like the timing chain jumped a tooth but personally I don't believe chevys jump time as easy as other engines. I had a 305 that the timing chain got so loose it wore a hole clean through the timing cover. With good compression and an accurate timing mark it should fire right up.

I was a little confused about a previous post about holding it to the floor to start it. That should not be necessary unless it is really flooded. It is harder on the starter to crank it with the throttle open.