Dear Garrett,
Regarding the ballast of the OC3-Hywind spar, a similar question was asked in the following forum topic: Further Details about the Floating Platform of OC3 - #2 by Jason.Jonkman.
The mass and cost of the gearbox and generator of the NREL 5-MW baseline turbine were not part of the original specification. I’ve seen a paper related to your question that may be helpful: Further Details about the Floating Platform of OC3 - #2 by Jason.Jonkman, but I’m not sure if there is a paper more directly applicable. I would reach out directly to the lead author of this paper.
Best regards,