When you get to that top tie and set up in DdRT, are you using rings or a friction saver? One of my favorite Canopy Anchors for SRT is using a Ring-ring Friction Saver with a stopper behind the small ring. I have a supple 8mm retrieval line in a small pouch which I tie to the stopper knot and then pitch the bag out to the crown. From your description, I would most likely do exactly as you do with the first 90' in SRT and switch over to lanyard/lanyard to continue, however once at the TIP, I would set the canopy anchor described above and climb SRT in the crown. This would allow more efficient use of the length of climb line at hand. Having not climbed conifers much above 130', I'm not sure, although this video does show a few things...don't mind the cheesiness.
The POV footage is 'moss'.
https://vimeo.com/57726543
SRT for spar work was just referring to felling out spar sections, and whatever length of descent between sections on a spar made easy by using the RW.
https://vimeo.com/57726543
SRT for spar work was just referring to felling out spar sections, and whatever length of descent between sections on a spar made easy by using the RW.