Boofus, it looks like with that upper the stock won't fully close. Not that that is bad or anything, but I'm thinking of doing the same with my M10 and am just feeling for info. Sweet looking setup btw.
I can't get a good pic, but I think the sights are too close. You have to stick your nose to the back end of the receiver to get the proper sight picture (front ring centered in hole). Still it's worlds better than the stock factory sights.
Most people use the G3 sites and not the mp5. A quick cure for this is to put the site on the #3 setting and drill it out a bit. You have to use the #3 setting because the way the site is angled there will be obstructions otherwise.