Performance increase from a few more cubic inches will be negligible. In stock form you're looking at .73 HP/cubic inch so at .030" over you're looking at maybe +4 HP at most. You won't feel the difference.

Are you considering any performance upgrades while it's apart? Head porting? Intake? Cam? Carb? I know you said you have new manifolds so probably no plans to upgrade those. If staying near stock HP levels I don't think you'd get much HP per dollar on better manifolds or headers unless you were needing to replace them anyway.