200+ isnīt that difficult. Iīve seen it from internally stock 1,9. Just get good set of rods and avoid too much low end torque. I had zero problems with head gasket, stock 1,9 metal with ARPs.
hi.. HP = RPMs X Torque (basically

)
all you have to do ist preventing Torque going down at high RPMs:
big plunger for short injetion time and shimmed mainspring peventing the
pump to reduce injection quantity up to at least 5500 rpm for 1,9L and about
6000 rpm for 1,7/1,6L, some extra timing advance would also be good.