1,3,4,2.

[Alan]

Shouldn’t worry. I get negative feedback all the while

[Tony Press]

I suppose when someone can't think of a reply it gives them something to do 

[nrzam]

Negative feedback deleted - I can't see anything in your post to bother me so I suspect I mis-targetted. My apologies.

Nrzam

[Tony Press]

Thank you 

[Chris KC]

The firing order is merely a matter of which lead you connect to which plug, and won't have changed when you swapped distributors unless you connected the leads differently. I suggest to systematically work through the timing set-up and components you have changed until you find the issue. One thing to watch out for is that not all DK4A's (if that's what you have) are designed to rotate the same way - A7 units are anti-clockwise (viewed from drive side). It should still start though and I'm not sure that would account for a backfire on cranking.