Which Ignition Box Do I Need

Ok I blew a head gasket a few weeks ago on basicaly a new engine. I'm thinking it was due to the ignition. I'm thinkin the ignition may not be up to the job of the engine, timing was set properly but at high rev's it sounds and feels like the timeing is off. I tried readjusting the timeing but i just couldn't get it to run properly at high rev's. At real high rev's i get a sound like marvels being thrown around in the engine, I asume this is light spark knock. So i know the timeing is off but could it be due to my orange ignition box also the car runs bad at times and good some other times. If i starte it up and and gas it a few times it's fine but after running it for a while sometime it would have a stumble when i press the gas then some time's its just fine all the time. My old all stock 318 would also stumble and run like trash some times and then other times it would be just fine. I'm starting to think my orange box may just be bad, or not enough for the engine. Should i go with the chrome box which is good up to 8000 rpm. Engine rev's up to 6000 pretty easy when it is running smooth, but when it starts stumbling it's hard to get it up to 3500 rpm. Engine spec's are at the bottom

Block: 360 .40 over
Pistons: Keith Black flat top 9.8-1 compression
Cam: Comp cam Nostalgia Plus .484 Int .484 Exh 20-672-4
Heads: J heads 2.02 & 1.60 valve milled to 68 cc
Ignition: Proform elect. Ignition with hp curve and Flame thrower coil 1.5 ohm Orange box.
Should I try an chrome box??????