A deep thanks to all who responded. I have decided to pass on the instrument as although it's a beauty, I didn't like the bright, brittle sound and am nervous about not being able to voice it down to my liking. The search continues!
My first grand piano, a Tokai G180 from the late 1980s, was rather brightish. But when I bought it I liked it, although I really didn't know much about what I was doing or what I wanted in a grand piano. I just wanted any grand piano and the Tokai was available and affordable.
Nevertheless, it was bought and paid for and sitting in my newly built music room (inclosed garage) and I was happy. By that time, my tuning skills had developed nicely, as well as a few other skills like basic action regulation. Hammer voicing was something new to me, but I was willing to give it try. Did some research, watched a lot of videos, and talked to some of the pro techs here, one of whom mailed me a training CD on hammer voicing, at his own expense, and wouldn't accept reimbursement. Thought that was pretty classy and generous of him.
Anyway, when I was ready to give it a try, I removed the action from the Tokai, filed/reshaped the hammers and got things set up with a small board underneath a section of the hammer tails, to support the hammers. With my new three needle voicing tool I started stabbing the he** out of the hammers with the voicing tool.
Poked my fingers and drew blood a time or two, but didn't get any on the hammers. The hammers on the Tokai were pretty hard and resisted the voicing needles, hence the hard stabbing motion. Otherwise, the needles would not have penetrated the shoulders of the hammers deep enough to have done much good. I didn't needle the strike point much, but did do some shallow needling there.
The end result was better than I expected. The Tokai was still a little bright but not as bright, by a lot. Not quite mellow, but way less bright. I was pleased with the results, despite sticking my fingers a time or two with the voicing needles.
One thing is for sure, hammer voicing is way more difficult and tedious than tuning.
Anyway, you did the right thing, Emery. You know what you want and it is always best to at least start out with close to what you want in tone and timber. I've had piano salespeople at piano stores tell they could voice a new piano anyway I wanted. I've always had my doubts about that. But I've never voiced new hammers. It may be much easier and predictable than voicing old, hard hammers.
Good luck with your piano search!