If this is base, then you definitely aerobic work. Just treat XC taining as that. I don't think it'll matter for you that much what sort of aerobic work it is, as long as it's not heaps of long slow running.
However it's important to keep up the speed work. If you're a speed based 800 runner, you should be doing a strong sprint session a week - flying 30s, 60s, resistance (sleds), short hills, all that sort of stuff. Couple this with a lot of drills, some plyos and definitely strength work (you can do a strength session after your sprint session so they don't take up too much time in the week).
Not sue if you can do this with a sprint squad, but work it into your program. And work logically - make sure the day before the sprint day is easy, and the day after it you can do up to about threshold but not much faster, certainly not speed endurance.