Hi Brian,
I have a 376 on a 53 plunger frame.
The 376 fits, but you'll not be able to have cable adjusters on the top, furthermore you will have to remove the airfilter, the 376 does not fit the rubber boot and the carby will hit the top of the filter housing.
You'll have to cut the filter housing off the bracket.
Looks pretty sweet.
I would probably stick with the original if you have all the bits.
Have never played with a Type 6, but have found the 376 easy to use.