Fresh 225 Promax down on power

[Iowafshr]

I bought a rebuilt .15 over 225 promax last fall. After my ginger break in period I've been trying to open it up and it doesn't want to pull past 5200rpm. My old 200 motor would pull much more with the same setup. It will only free rev to 6200, then it just seems to hit a wall.
Plugs look good
Swapped switch box, stator and trigger off an old motor that I knew were good.
Timing is set at 8 and 23
Fuel pressure is 38psi
Compression was almost all spot on at about 140lbs

I'm leaning toward possible ECU issue.
Since I don't have another 225 ecu to test, how dangerous is it to put my 200 promax ecu on it?

Also I'm not sure what tuner is in it. The tuner ran fine on my 200, so I wouldn't expect any different with this motor, but I could be wrong.

Could still having a somewhat rich oil mixture in the tank after breakin hold it back?

TIA
Jason