First and foremost, please allow me to extend my deepest condolences to you and your family in this time of loss.  These hardships are never easy. 
  
I agree with your choice to go with a turbo motor, and the RB is a great platform to build a stout, powerful car.  I too have been reading up on the inline engines in this forum, and I also agree that the RB25 a solid choice for early Z performance.  You're doing a great job of documenting cost and work.