new trans for 85 wideglide

[85WIDE]

I have and 1985 wideglide, the trans has a tapered shaft, which is damaged. I would like to put in a 6 speed. But there is very little after market stuff for this year. So I would like to know if a newer primary will bolt to my motor. I looked at a closed belt drive.

 

[85WIDE]

I have seen some of these, but most are for 1979-e84 and then 1990-2008 for dyna's. Or they are for softail's. If a softail primary is longer and will bolt to my evo engine that would be great. I can make it work. I have been wanting to lenghten the frame but i don't want to do just the front like everyone else.
thanks 85wide