Out of the Loomis line, if you want one that will spey/roll and overhead cast well, I think you'd be best off with the Skagit/Dredger series. The Scandinavian Series is the fastest of the three and not really intended for Spey casting.

Another option is to get a fast rod and overline it to slow it down. The differences in rods and lines are so challenging to understand I would really consult an expert on this.

You also might want to check out speypages.com