Of course it does, the inequality would just be modified if you use different numbers to label "spin-up" and "spin-down" measurements. Look at the step at the top of p. 406 (p. 4 of the pdf) of
Bell's derivation, he invokes equation (1) which says that A(b,λ) = ±1 in order to justify equating the integrand [A(a,λ)*A(c,λ) - A(a,λ)*A(b,λ)] to the integrand A(a,λ)*A(b,λ)*[A(b,λ)*A(c,λ) - 1]...in other words, he's using the fact that A(b,λ)*A(b,λ)=+1. If you instead labeled the results with +(1/2) and -(1/2), then A(b,λ)*A(b,λ)=+(1/4), so that step wouldn't work. Instead the second integrand would have to be A(a,λ)*A(b,λ)*[
4*A(b,λ)*A(c,λ) - 1].
Continuing on with steps analogous to the ones in Bell's paper, we can then apply the
triangle inequality (which works as well for integrals as it does for discrete sums) to show that if P(a,b) - P(a,c) = \int d\lambda \rho(\lambda) A(a,\lambda)A(b,\lambda)[4A(b,\lambda)A(c,\lambda) - 1], that implies \mid P(a,b) - P(a,c) \mid \le \int d\lambda \mid \rho(\lambda) A(a,\lambda)A(b,\lambda)[4A(b,\lambda)A(c,\lambda) - 1] \mid. Since \rho(\lambda) is always positive and A(a,λ)*A(b,λ)=±(1/4) that becomes \mid P(a,b) - P(a,c) \mid \le \int d\lambda \rho(\lambda) (1/4) \mid [4A(b,\lambda)A(c,\lambda) - 1] \mid, then since 4*A(b,λ)*A(c,λ) - 1 is always equal to -2 or 0, its absolute value is always equal to 1 - 4*A(b,λ)*A(c,λ) so we now have \mid P(a,b) - P(a,c) \mid \le \int d\lambda \rho(\lambda) (1/4) [1 - 4A(b,\lambda)A(c,\lambda)] or \mid P(a,b) - P(a,c) \mid \le \int d\lambda \rho(\lambda) [(1/4) - A(b,\lambda)A(c,\lambda)]. Bell then notes that \int d\lambda \rho(\lambda) [-A(b,\lambda)A(c,\lambda)] = P(b,c) and since \int d\lambda \rho(\lambda) = 1 this gives an inequality equivalent to the one Bell derives:
(1/4) + P(b,c) ≥ |P(a,b) - P(a,c)|
With the measurement results labeled +(1/2) or -(1/2), there's no way
this inequality can be violated in a realist theory that respects relativity.