Not knowing anything about the airframe (and ignoring the engine for a minute) you still have what I hope is a valid STC for a 150 HP conversion. Other things like, LR Tanks? Avionics and such would give more basis for an opinion, but a Cam Change is not the end of the world.
I did it on my O-360 when we suspected it was an issue and due to the type of accessory drive on my model, we even changed that out. Let's say you have $4000 into a cam change and $5000 in other "stuff", you could still have a nice 150/150 for less than $30,000 which is not the end of the world.
