Most people who "want x amount of power" are actually talking about torque, and don't know it. I think you need to ask your friend what is he expecting form this 250hp engine.
Also, a late euro spec M110 has quite a bit of poke (185hp), an can be easily converted to run modern ignition and electronic fuel injection. Such mods could allow you to play with ignition timing a bit, and achieve low 200hp, and a very very rev happy engine.
It would cost much less, and be a lot less trouble.

EDIT: Also, the cam timing on this late m110 is very mild, because of a limitation of the original k-jetronic injection. With a modern electronic injection you can dial in a little bit of valve overlap an get even more power.