I would also recommend the EMAD. Although the Superkick II is the top choice on this thread, I think it might be a bit too heavy for folk rock.
The EMAD is a solid all-purpose kick drum head that will sound awesome for folk rock. It comes with two attachable foam rings that will let your drummer adjust his kick sound.
For a slightly warmer sound, I would actually recommend the EMAD coated head, which I think your drummer will love.