Absolutely anything you want. I use a follower in my so everything is single feed. I have a 204/223 bolthead with the spacer I got from SSS. It becomes whatever you need. It has been a 223, 22-250, 22-250 AI, 6mm Rem, 6 Rem AI, 6BR, 30 BR, and 308W depending on the day of the week and my need. I am building my 9 yr old a 223 rifle based on a LA because that action can become whatever he wants/needs in the future.

In terms of 7mm, I would take a look at the 284 Winchester. Seem to remember someone doing really well with that round in F/Class a few years back. I think the 284 W is making a come back at 7mm contender.

Luck, Tim