Honestly, I would go minimalist on it. Accessories are great, but they also add a lot of weight to an already heavy weapon. A longer tightbore barrel would be good, with a lightweight silencer to cover it. I would also put a forgrip on it, as I have one on that MP5k and it is a lifesaver. It can be used to stabilize the weapon while using it, as well as putting your wrist in a much better position while shooting, which can be helpful with fatigue. I carried an M4 for a year or two before selling it cause it was heavy and I kept gripping the magwell, which didn't help my accuracy at all and ended up making my wrist sore after holding it for long periods of time.
Also, for the love of God do not get Magpul crap or I will unfriend you on Facebook, lol. Magpul products may be decent and while Haley and Costa might be nice guys, I really don't get the rabid fanboyism surrounding their merchandise or them. EOtech sights are similarly retarded and should be avoided like the Ebola plague. Although if you put three red lasers on a single switch, kinda like the Predator targeting laser, you will be the best person ever.
In short, keep it simple and don't clamp a bunch of junk on there. You want a classy weapon that Agent 47 would be proud to use, not a Transformers-like collection of railed crap. Seriously, why do all the Autobots look like something that got stuck to a giant magnet in a scrapyard? Am I the only one who sees this? I may have a tumor.
