In Line diesel pump

I am converting an 1985 Firebrigade truck for overlanding.

Spec on the truck:

Aircooled 6 cylinder in-line diesel 6.128cc turbocharged (Deutz BF6L913)

Max torque at 1450RPM 550Nm(?)

Power at 2500RPM 160hp

Fuel delivery 6 in-line pump (mechanical control)

Goal: more torque and power (250hp)

I have allready new injector installed, 4hole instead of the original 3hole. 5hole are available at a cost. Unfortunatly I have no data on the turbocharger.. Anybody ideas on how to go from here?