408 wont run

My 408 I built ran beautiful on the engine stand and now I have it in the car it wont start. When I turn key it starts momentarily albeit very rough then dies. It's not a fuel problem as I can see the carb has plenty of fuel.

I feel it is an electrical problem. At first I thought it was a lead mixed up or dist in 180 degrees out but I have checked them a couple of times and is correct. I have a MSD Digital E curve which I have locked out, dials set to 0 0. All the original electronic ign has been disabled and dist is wired to MSD recommendations. Any ideas?