[Rick Parker]

A good item if you do not already have them are the vibration isolators that mount on each corner. These boxes do not like vibration, shock or excessive heat. You might re-evaluate where it is being mounted with regard to heat, give the fact that youare running a 427 FE (High heat source). I once had a fresh coil go bad and attempted to blame it on the control box. The amount of current that these boxes develop and the fast rise time necesitate that the ENTIRE primary and secondary system be in top condition.
They will even burn through the top of the rotor and into the distributor shaft seeking a ground circut in lieu of going to the plugs through the cap and wires. Recheck the power source,
have you removed the ballast resistor or resistor wire feeding
the switched power to the box since you removed the dual point
distributor? Pull the (non switched) power (10 gauge red wire) direct from the starter solinoid (hot side). The MSD product is one of the best available. EACH control box is put through a burn in cycle for several hours under simulated operating conditions
before it is packaged for sale. These symptoms often turn out to be something minor that create a larger problem.
Good luck chasing ignition gremlins!
Rick