Regarding international use of the Arrow, I've seen documentation that the developed Arrow Mk.II was offered to GOR-329/F.155T and, in a modified form, to GOR-339, the TSR-2 spec. Avro Aircraft and Cold War Aviation has Randall Whitcomb's interpretation from what he was able to find and from interviews with Jim Floyd, it shows the Arrow with long-range underwing tanks and an ASM resembling a scaled-down Blue Steel carried semi-recessed in the detachable weapons bay. I've seen some other documentation that mentions that this proposal included beefed-up structure and skin.
Further note, one variant of the Arrow, with two Red Dean missiles in the weapons bay pack, is illustrated in Battle Flight.
Personally, I think that continuing with the Sparrow II was a mistake, the electronics of the time just didn't permit fitting that much capability into that small an airframe. Heck, 20 years later, Hughes had a devil of time doing it with AMRAAM, though they finally succeeded.