Suggestions on performance upgrades for 225

For your aerodynamic-as-a-brick van,more compression is paramount.
A free-breathing intake/exhaust will get you to cruising speed faster.
The tune will make it shine.
That long stroke motor can take advantage of more cam, but the Dcr has to be set at the time of cam selection for best results.
Of course, just gears will wake it up,all by themselves.