Kind of stepping on much of what has already been said:

I would pull the head and have a valve job done, obviously replacing the head gasket; make sure the belts, rollers and front seals are fresh; water pump is a good idea to do at the same time, and thermostat. Rod bearings and bottom end seals (oil pan gasket, oil cooler gasket set, rear main).

Could have a leakdown test done (compression test is much less telltale) and if numbers are poor past the rings, re-ring it when the head is off and the bottom end pulled to replace rod bearings.

All coolant hoses and high pressure intake hoses (downstream of the turbo) are suspect with age/mileage. Get rid of the cat, this will wake up a high mileage 951. May want to put in a new fuel filter.

Turbocharger may need to be rebuilt, but would wait to see how much oil it blows first.

Check/replace the rubber fuel lines
Control Arm balljoints
Check the motor mounts
Check the clutch
CV joints and boots
Other suspension and swaybar bushings
Wheel bearings
Trans fluid

Have a spare DME relay and Cycling Valve ready to go.

Before adding much power to the car for track use, plan on upgrading the suspension first. M030 parts wont be stiff enough for horsepower anywhere near what you are talking about for a dedicated track car. You would want to be nearly triple the stock spring rates and either revalve/rebuild the konis or get some better dampers.

And as mentioned above, good to put some safety equipment in the car at the same time.