If you run it in too gently you will just glaze the bores and it will always use oil. Can you lock it in any gear? i.e. get rid of the freewheeling? Turn the overdrive off?
Then accelerate briskly (keeping the boost to a minimum) to 5 -6k revs and then lift off letting it go down to 2-3K and repeat. Watch the temp guage. Listen for any strange sounds, watch the temps and now and again look under the bonnet for any leaks etc.
if there are no problems kep increasing the revs to 5, 5500, 6000, 6500 without flooring the pedal. I would do my running in in one day and then get the car back asap to get the head retorqued and change the oil and filter.