I never, ever use any extract other than pale or pilsner extract. If you use a generic "Dark" or "Amber" extract, how do you know what's in it? Does the amber extract have crystal malt in it, or munich, or pale malt and just enough roasted malt to make it amber? All three would be drastically different. And beyond that, the amount of specialty malt you have here, plus dark candy syrup, is more than enough to get a strong dark beer with just a pale extract. My homebrew shop doesn't carry a Munich extract, but assuming it is an extract made from 100% munich malt that sounds great for this beer.
So first thing i'd switch the amber extract to light or even extra light/pilsner extract.
Other than that you have an awful lot of specialty malt in there. Many of our favorite belgian breweries (St Bernardus, Rochefort, and more) claim to only use base malt and dark candy sugar as fermentalbes (to what extent they consider Munich base malt, I'm not sure). What you have might be a little cloying in such a big beer. Personally I'd cut the Special B to 1/4 lb and take out the chocolate completely. The dark syrup and special B will give you plenty of color.
My 2 cents.