Here's what Mark from GTpumps had to say
"you have to balance the whole assembly. You need to check the bearing clearances and the condition of the bore and blast everything clean. We also VSR high speed balance the cartridge once assembled. Our normal rebuild cost is $660.00 which includes the rebuild kit, if you supplied the 9 blade we could fit that."
Given that, I'm going to wait until I have the turbo off while the engine is getting rebuilt (once I finish collecting parts).
I've been toying with getting an FP green also, but I'm not a fan having a high boost threshold on the street, hence the thought of sticking with the 20g, and getting the 9 blade to give the turbine side a little more flow. But then again the engine is going to be 8.5:1 and 94mm with a ported head and big valves etc, and I want a turbo for 30 psi on E85 that doesn't drop off too much up top. Decisions, decisions.