Bigger rods are always better and stronger. Bigger rods mean re-balancing.
Sounds like you have a good set of 3/8 rods. Have no idea your intended power or rpm. I will suggest from personal experience in a very high hp per cube engine from years back to keep rpm below 8,000 rpm and to cut to neutral at finish line for rod life.
I will not even say what power level I used them with and got away with but it was substantial. The fact of the 3/8 rods is what kept me from revving higher.
I am not advising to do what I did just simply telling you I made them live. I protected my rods by not letting the engine see any decelleration forces at all.
Ed