Ditto to what jonwepa said! If you had the realtime ecu it would be even easier. And if the timing is off, that could answer ALOT of your issue with the hp loss. A wideband, and some consult info (you'd need a consult cable), and a rom burner and you'd be set (with the calum basic ecu)!
Then once you get the car tuned based on the wideband data, you can take it to the dyno and finish up your tuning for hp (but you'll need the burner).. Again, realtime IS the way to go IMO.