dpending what you want ot build any conbo will work but for longevity I like the 512 for the longer rods , it gives a decent 1.72 rod ratio , you get less piston side loading & more combustion durtaion , longer burn time more torque etc with longer rods/ rod ratio , for racing the larger displacement May help power but for street the 512 offers long life & more then adequate power , basically more CI is Nto nessisary a big advantage
I just did a 512 with ported factory Iron heads , basically you cannot leave the line without the tires spinning no matter how gentile you are with the clutch , , it has yet to be dynoed but should be int he 650 ft lbs torque range with 575 hp , we are also using a flat tappet solid cam with close to .600 lift , I can spec a cam with over .600 lift as a flat tappet solid using 1.6 rockers