I'd go with the Mich comp 4 or comp MS front, with a T63 rear. Alps really seem to like that combination. Cheap too, from mytyres.co.uk. (£25 less than MT21s)
I've a set on order to replace the dire "Army Specials" (Mitas ??)that are on it. They're OK in mud, but on anything else it's a bit scary! Gravel limits at 60 before there's a massive wobble.