Yes. I'm doing it in my 6v 49 3100.
The truck is still 6v witt a couple 12v circuits added to power a tach and power outlet.
I used a 10a 6v to 12v converter off of Amazon (available on ebay also) and added a separate fuse block to isolate it.

I picked the 10amp incase I wanted to add a radio.

Dave

1949 Chevy 1/2-Ton 3100
1949 GMC 1/2-ton 100
In the Stovebolt Gallery
More pix on Photobucket
Video of the 216 running
Video of a Winter Cruise