Hi Dick,
An Icom 2AT is perfect for the GW as it can run on 12 VDC and has many accessories available for it...
You will need a boom mic/headset to cannibalize for the boom mic and then get some nice walkman headphones and do the same to them for the earpieces..
Find a esthetically pleasing way to mount all that stuff to the helmet both inside and out and then use a coiled cord for the hookup to the radio... I have an old Icom PTT that I got at some hamfest years ago that I wired up to key the radio and I mounted it on my left handlebar above the turn signal switch...
it has a cable from it that has the molded plug that fits the Icom/Yaesu radios and an external jack for the headset mic to the helmet...
I will post some more detailed pics of my set up in my album.. take a look and if you have any questions, let me know...
Oh and I used a Diamond NR 770H NMO antenna on the bike for dual band use and so I could get a little gain from it (3 DBi at 2M and 5 DBi at 440) since the FT 470 only puts out about 4 watts....
Rich