Simple polymer blends were studied by simulations with the intent of probing the response of structurally asymmetric chains to progressively stronger attractive interactions strengths. It was found, for miscible blends, that the intermolecular pair correlation functions, the g(r)'s, varied by less than 10% from those of the associated blend with strictly repulsive interactions. When used for the purposes of calculating changes in pressure due to the attractive strength, the g(r)'s from either the repulsive or attractive systems could be used interchangeably in the perturbation theory. On the other hand, calculations of the enthalpic chi parameter were sensitive to small variations in the g(r)'s, although, at least for the systems studied here, the associated predictions of the phase boundaries were relatively insensitive.