Just got my stamp today and I am trying to figure out what gas block will fit under my SR 15 E3 rails? I was looking at the noveske barrel and lo profile from them and am wondering if it will fit. 
link to noveske barrel and gas block combo http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?item_id=b-115-556&cat=158&page=1&search=&since=&status=
I recently installed a URX II rail onto a Noveseke upper with the same barrel /gas block shown. The upper part of the rail system fit (make sure you install flash hider/break before you install barrel, you will not be able to tighten it with the URX installed). The lower portion of URX would not quite fit. The heat shield in the lower section hit the back of the gas block and would not fit. A little file work to the bottom/back of the gas block solved the problem.
If you have an SR15 E3 and are going to put one of the Noveske barrels you will need a standard bolt for your rifle also.