Thanks for the replies. I reckon we'll just shim it up and see how it goes, its cheap so if we don't like it we can always look at other options and we're not really out of pocket. We're thinking of giving it about 3mm of preload as well.
The only reason I was thinking of running semi's on the front is because we already have some Dunlop 03G's, otherwise I probably wouldn't bother. I was wondering initially if they would have trouble getting up to temp but after thinking about it, from the couple of times I've been to Baskerville they seemed to work OK from cold. I guess the main thing I'm concerned about is how quickly they will wear, so how much do fronts wear when drifting?