I've just read this whole thread for the first time and wanted to congratulate you on creating a work of art, I think (though others will probably disagree) that this is a serious contender for Bike Of The Year. The dedication, technical skill and aesthetic vision that you have applied to this project is a rare and wonderful thing to witness and I join the other posters here in anticipating a stunning final build.
As to choosing a Bear Valley - I have spent hundreds of riding hours on Bear Valleys, not the lightest bike stock but a wonderful XC ride and with sensible upgrades they can run with the best of them. For me it's the quintessential early 1990s Californian mountain bike - I just have to look at those decals and it reminds me of summers long past.
Thanks for the nostalgia trip and good luck, I can't wait to see it on its wheels.
1986 RM Ritchey "Canapurna", 1991 Marin Eldridge Grade, 1990? Vitus Futural CX, 1995 TREK Singletrack 950, 1996 Muddy Fox Monarch Team, 1997 DMR Trailstar, 1993 Pro-Flex 853, 2001 Santa Cruz Chameleon