Personally I'd be going
Kelly
O'Donnell Mugabi Solholm Carroll
Slattery (if available) Maguire Goss
Spittal Van Veen Tierney
If Slattery is unavailable, I'd be moving Tierney back to midfield and playing Shields up top. If Spittal is a creator of chances as his Ross County stats last season suggest, let's get him where he can do damage. Tierney is one of the few fearless players in the squad who will run at players and not just take a touch and toss a hopeful cross in or play a safe pass. Rest of the team picks itself due to lack of options.
Morris can sell the pies. Not anywhere near good enough...