i don't think it makes any difference whether it's flat or roller. you don't do your homework on parts and cleanliness you're setting yourself up for a problem. from i can see the cam didn't go flat; the engine was probably dirty from machining and not cleaned and there weren't enough checks done. before i bought any parts for this thing i'd mock the crank and cam back up to make sure there running parallel. that leaf chains cam sprocket may not be correct and the timing chain/sprockets should be checked to make they're running perpendicular to the crank. take the oil pump apart. look at every nook and cranny in the engine.