I recently had the dist gear on my msd billet ready to run dist fail after less than 1000 miles. I have a ZZ3 350 with vortech heads running a comp cams  XE282HR part #08-432-08. I've been told this is a cast core cam. I had a reputable engine builder here in Tucson freshen this engine up for me. The cam and dist were new. This is all in my 72 Nova. The failure was sudden. After pulling the dist. 3 or 4 gears on the dist look completely worn. The other teeth look ok, showing only minimal wear. I am running a high volume pump. I did some looking around on the internet and saw that other people were having the same problems with their comp cams roller and msd dist. I asked the guys at comp when this engine was going together if I needed to run a special dist gear and was told that I was ok with the msd gear. I'm getting conflicting answers from comp. One guy says I need the melonized gear another guy tells me to run a regular iron gear. What dist gear do I need to run with this cam? What about comps poly gear. I'm hoping the cam gear is ok. Should I switch to the stock oil pump? Was the high volume pump adding undue stress? I will inspect the cam gear by rotating the engine by hand. If it looks ok I will pull the oil pan and clean it out, replace the oil pump if necessary, replace the dist gear and put it back together and hope it lives.  

First, yes, switch to a stock oil pump. For a street engine, the high volume pump can hurt power because of forcing too much engine to certain parts. Now, when you installed the new oil pump, did you pack it with grease? It coudl be that you packed the pump too tightly, and at inital start up it created extra resistence ont he distributor gear that caused the premature failure.

Now, on the gear/cam compatibility, if the cam you have is a cast cam, you want to use a cast gear. If the cam is a billet cam, you want a bronze gear.

The problem could also be in the distributor housing. Have your engine builder check the wear pattern on the distributor gear and make sure it was properly engaged on the cam. If the housing is out of production tolerance, it could have the gear offset, which could've caused the premature failure.