the current standard for radial road race tyres is teh Hoosier R6.
Grassroots motosports had an issue a few month back and they had an untested i dea that the hankook z214 would do well on a lighter car like a miata. their test subject was a WRX wagon. I know a local autoXer using the z214 on his z3, he likes them. I know a bunch using the v710s, they are unwilling to commit to several sets of hoosiers per year. V710s in 14" are on closeout at tirerack. Attn steveT!
look into the SCCA D/E mod yahoo group. there's a nice thread thats active right now concerning camber angles and has someinfo air pressures regarding bias tyres.
from the guys who did my alignment, as little camber as possible is desirable and when i spoke to caterham usa (cody iirc) his advice and experience was to stay low with the camber, close to book tolerances, and go a little more on castor if possible.
my opinion is traction is traction and wider is better.