as long as both tires are the same on each axle, you should have no problems.
bias [especially skinny ones] will tend to "hunt around" a bit on "rain grooved" roads, but dialing in as much positive caster as possible, and toeing in an extra 1/16" will keep that to a bare minimum.
over the years, i have ran just about every combination of tires you can imagine, and on all types of cars, and have never had a problem running radials and bias tires together.

as to the speed rating on tires, it is xx[x] mph for yz amount of time.
so even if the tire is rated for 95mph, the few seconds it spends at 125 will not be a problem.
my opinion only ! your mileage will vary.