Eljaro To start with there have been many problems with the cap and rotors on the MSD setup. The carbon pile in the centers are breaking or burning out. The center contacts are falling out of the cap. There is no spring tension on this contact from the distributor cap. Carbon tracks are happening inside the cap and causing miss firess. What spark plug wires are you running? Check all the ends and make sure they are tighen on the contacts. Also add a little grease, sillicone to help with heat transfer. You didn't say how old the coil is? this could also be another problem that it is breakin down under high rpms. Where is your coil mounted and which one is it? Is it mounted vertical or horizontal? Mounting a coil on a motor is not a good thing either. The vibrations and heat the motor gives off, shorten the life of a coil. To start with, drill a large hole in the top of the distrib cap in both sides of the #1 terminal. As said before, you need to faze the distrubutor to the motor first and then setup the timing. I carry a whole setup in my car for MSD ignitions. 6AL box, HVC coil, Cap and rotor and electronic internal parts. You said you have a miss, recheck the cap and rotor or install a new one. Some of the guys here are using a stock cap from GM I think and it works better than the MSD stuff. Do a search for this problem. Faze the motor and then start to replace parts. If the coil is on the motor or horizontal this would be the first thing to check. MSD system beats the crap out of coils and distrubutor caps and rotors from the long, high outputs of spark. It's like welding. The car will run fine with the holy cap on it. You may also see the problem too.
Rick L.