You need RPM's not displacement-
A Jett-50, YS-45 (Piped), or Rossi-53 would make that plane a monster....
A Rossi-60 or older YS-60 and full pipe would be crazy- and if you want more you need to be looking for DF engines-
I love that question "How do I make my mustang scream!" I mean a YS-63 would move out, but the 2 cy. engines above will be both fun and un-nerving!
Keep us posted!
james