It depends a lot on the grip levels of the track as well. Even asphalt has varying levels of grip. The tracks we ran were older, less grippy. But, for Vega we rolled usually 60cc.
What we rolled was broad, a lot of times you could get away with just Hotlap II in summer. Spring and fall you'd mix something slightly more aggressive to fire the tires , but mostly running on the Hotlap II to maintain consistent temps. We tried a few different tracktac preps. SST, SQS, Kryptonite, all worked great inside and out on Vega. Just depends how much grip you need. 30-60cc is about the most we ever used.