7 lbs is excellent for a long rail like that! Not much more than my LW DD upper with MOE furniture.
I went with optics ready in my ArmaLite upper (railed gas block) but like MJ have found the fixed front sight base on my DD upper not to be a problem with my 3-9x40 scope or RDS.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek