It does vary for each roller maker. Here (US) there is anywhere from a 10% to 25% range for deduction for whp readings. The DynoJet I go to is about 15% lower than crank numbers...I am told. Without knowing what the reduction of the roller you were on is...it is safe to assume approximately 15%.
To summarize:
if it is a stingy whp roller = 360+bhp
if it is a generous whp roller = 360-bhp
You are likely between 355 and 365 bhp.
