Blacked

I recently had a rod come loose from the crank in my 2003 496. It damaged the crank and block soo I bought a used shortblock with 120 hrs on it. I am keeping it the stock 375 hp, I just want it to last more than the 200 hrs that the last one did. Are the rod cap bolts weak from factory or was mine breaking just me running it too hard, should I open up the shortblock and replace anything or just bolt on my upper and move on ? My first 496, not a fan soo far but I guess I will give it one more chance.