All of the intake cams are the same, all B660.
I searched on the forum here, it appears the stock Capri exhaust cam is also marked B660.
What exhaust cam is in the car?
If it is down on power it could be something else too, related to the work they did. Head replacement is fairly invasive.
Could be the timing belt timing, poorly adjusted throttle cable, pressure leak in the intake piping, etc.