As I read your original post, there was no fire as the ignition was off.
How were you turning it over, with a socket on the crank?
My vote is also timing. Check that you don't have it 180* off.
C
Is there a difference? When I was shopping for these parts earlier this week, the web sites do not even list a big block as an option.
I think you will find you have a choice of "1".
C
Check to make sure that the plug wires are on correct. This sounds like you could have crossed a couple of them when you put new plugs in or changed the distributor cap.
C