You could use the FP gearbox and a 2:1 reduction to get ~the same (2 and some change will give you the reduction you need). My brother posted a picture of a nice easy way of interfacing with the FP gearbox a couple days ago.
EDIT:
http://www.chiefdelphi.com/media/photos/36316 There is the picture and description of the part. If you would like more details I have another 3 of those sitting in my shop right now and can measure them.