I'd suggest you cut the corner and route from around Edzell northwards, skirting to the west of the Aberdeen zone. Once you get to around Alford or Huntly you'll be able to determine whether to route NW direct to Inverness or take a more coastal route.
It is a long way over water at 2000ft if Tain Range (D703) is active, as it usually is on weekdays, so Inverness northwards is likely to be the only possible route. R610C is only active 1500-2300 Mon to Thu which gives plenty scope for flying through it. If you are there during its active times you can ask for a crossing from Tain Range on 122.75. Same applies for R610D further up the coast.
Don't worry about taking enough fuel for Kirkwall though - there are plenty of suitable trees to land in just north of Dundee.
NS