I built a 408 stroker with a Comp Cams roller camshaft that had a hardened cast iron gear. I used a MSD distributor that had a hardened cast iron gear. Unfortunately, the distributor's cast gear had a rockwell hardness that was less than the cam, and when we were breaking in the engine on a dyno (thank goodness I chose to find the flaws of a new engine on the dyno rather than in the car!), the distributor gear disintegrated in 10 minutes. The good thing about most engine dyno's is that they are usually equipped with an
oil filter system that removes even the smallest particulates for analysis...at least this one did.
Anyway, according to MSD, when you replace the gear, you press on the new one and drill for the new pin. This obviously limits the number of times you can replace a gear! So, I had the machinist hone a bronze gear and we used the original pin position. After about 15 minutes on the dyno, the bronze gear showed signs of wear as well, although nowhere near what happened with the cast gear. We estimated that the bronze gear would last about 10k miles, then need replacing.
We then tried a steel gear from Comp Cams, and it's worked flawlessly ever since.
One item of real frustration: We made repeated phone calls to Comp Cams and MSD to try to get them to recommend the proper gear type. Each time we called, we got a different person and a different answer.
I guess my point here is that it's really difficult to answer your question without knowing all of the facts and specs. Folks that say use a cast distributor gear with a cast cam gear could be leading you down the same path that I started...remember the rockwell hardness issue?
But my opinion would be that since you're using a non-roller cam, your cast distributor gear should be ok.