A 1/48 Jayhawk? That's what the market is missing!
Between the position of the tail wheel, the main cabin windows & doors and external fuel tanks, you might want to consider the Italieri 1/48 SH-60 as your staring point. I think the real Jayhawk is based off of Sikorsky's navalized SH-60 whereas the MH-60G at the end of the day is a heavily modified standard UH-60 airframe. Cobra Company even makes a Jayhawk conversion kit for the Italeri SH-60 http://www.cobracompany.com/48033.htm
I don't know about decals though. You might be able to co-opt some from a 1/48 Dolphin kit.