This is honestly a great build...I've tried quite a few others builds for this variant , but this one really shines. I used the ER PPCs with AMS and an XL220.
I changed it around a little bit (med lasers, and dropped a half ton of leg armor to fit an xl 235), but so far I am really digging this build. I still think blackjack is kinda a crap mech due to the engine restriction unless you are artificially tonnage limited for a tourny or something due to its speed (a CTF-3D or even a TBT-7M can do this better in almost every single way with the tiny disadvantage of lower mounted weapons), but this is a solid build if you are like me and just looking to elite a new mech line for the fun of it.
Slapped AMS on the mech by shaving off one DHS and some armor. Also moved the JJ around to better positions. Still thinking about ER PPC instead but decides to keep the original. Also, maybe 2xMLas at the arms instead of 4xSLas, but I am yet to be sure.