The top rail portion ties in where the folding front site mounts and the lower slides in the same way your existing lower rail portion does, its just longer.
Overall length of the rail does seem like it would interfere with your suppressor and also the gas block. If it were just the gas block, I would say, replace it with a low pro and call it a day.
Have you experimented with your optic eye relief and mounting to find out where it needs to be?
Off hand, I do not recall what the minimum distance between day optic and PVS27 "should" be but I have played with different distances between the two and didnt notice any major changes. The only downside I have noticed with mounting the 27 very close to the scope is the flip up lens covers not being usable.
You may just end up having to swap the rail and maybe the gas block out to better suit your needs. Please post final setup pics for reference once you figure it out.
Good luck