Special Forces ideas

I've decided that I need some special forces types for certain missions.
 
I do have a set of Rebel Mini's SAS, but they're more of an anti-terrorist or hostage rescue mixture of figures with gas masks and anti-flash hoods, armed mainly with pistols and SMGs.  The force I most commonly use in games are my NAC Marines from GZG, so I'm going to use them as the base figures.  The majority of their equipment will be the same as that carried by the regular troops, so there are only two main changes that I'll want to make to them:

1) Head swaps.  I'll be replacing all the heads with some of GZG's replacement heads, probably those which include night vision goggles.  I haven't decided whether I'll have 8 with goggles or split a pack so that 4 have goggles and 4 have something different.  I could give them gas masks, though I've also been considering some MPs.  If I get Jon's other pack of replacement heads I could use berets or something similar to help differentiate them from the other Marines.  Of course, I could just get the "NAC Marine in Berets" pack for my MPs, which would be a whole lot easier...

2) Weapons.  My special forces team will use the standard marine assault rifle, but with a large sound/flash suppressor attached.  I plan to cut off the existing barrel and drill a hole into which I will insert a thin piece of brass rod.  This rod will act as an attachment point for some brass tube to form the suppressor.  I could fix the tube directly onto the barrel as it comes on the figure, but I don't think that would stand up to much handling.  I don't want to be forever hunting for the loose suppressors rolling around in the figure case ready to glue them back on!

An artist's impression of the finished product.  I'm happy to report that the artist has been given the sack after producing this poor quality image.  Hopefully the physical result will turn out better than this (and without a curious greenish stripe along the bottom).

Colour scheme will need to be different from the normal troops, probably a dark grey/black so that they look suitably menacing.  If I go for MPs as well, they'll be painted to match the regular troops, but with one or two changes such as coloured shoulder pads to emphasize their
importance.  (I imagine they'd have coloured, elasticated patches they can pull over the armour panels, easily removed if they get involved in fire combat.)