Not there is really anything to add, but as far as engines go, since it was mentioned, I highly recommend the 340 STD. 350 would get you an extra heat sink, but that's an awful lot of weight, and not much extra maneuverability for just one more heatsink. Once you get past 325, and YMMV, you start seeing some pretty big gaps between engines worth running.
I'm also a fan of twin UAC-5s for brawling. Cover or not, your opponent is trying to do the best they can to not get hit, and if they succeed while you're running the 20...well, that's an awful lot of damage you're just not getting. Twinc UAC can put out the same amount of damage, and then some, in the time it takes a 20 to recycle, with the added insurance that at least something is landing on target. But, as mentioned, it's a gamble, and I'm not going to parrot the other combos that compete.
In regards to armoring arms, I'd just have to agree to disagree with some of the aforementioned points on putting full points on them. I've been able to get my arm blown off instead of my torso more often than not. Sure, maybe not enough to actually justify full points on the arm, but the times I notice, I really notice it. Legs....yeah, i'm just a dummy that can't stand shaving that extra armor off.
And just to spam you with another build;
DDC-Electronic Nightmare. Now, the armor isn't adjusted, as everyone has their preferences there, but I actually move an awful lot of it up front (Rears are 20 sides, 30 CT). MPlas's are bad, and I should feel bad for running them, I'm sure, but imo, are better for shaving lights off of you than any other laser. With 15 heatsinks, you can pretty much swap to just the pair, and stand on the firing trigger while engaged with a light, and not overheat on any but the hottest zones.
Streaks, just because they're more reliable than srms, and because I spent money on a BAP, darn it. But not only that, it allows you to 'surge' your counter ecm. With the faster lock, you can drop your bubble, disrupt their's, pick up lock, fire, and re-engage your bubble before most boats can have missiles on you. (And it makes you feel all skill-pro when it works).
IF nothing else though, my biggest suggestion for actual brawling is lower damage, higher dps. Brawling is getting up in something's face and only one of you is walking away. Leave the bigger guns to snipers and fire support. You need damage on point and on target.
That given, regarding modules, my other bit of advice is Zoom, Target Info, and a Seismic, fourth slot your choice (Arty and Air are great given ECM is pretty decent at hiding you, and keeping them from seeing it if you drop it behind things).
Zoom for those pilots that like to overheat, pop in, get the accuracy boost, slam their weak stuff, unzoom. Info....is iffy, some people hate it, some love it. I obviously love it. Lots of brawls end much quicker because I know I don't need to waste any time trying to get a missile lock, Lay into that left torso with the 5's before they notice...profit. Seismic; You are in what may not be the most devastating, but one of the most 'omfg, kill it now' 'mechs on the battlefield. Any pilot worth their c-bills is going to try and engage you from behind, and stay back there as much as possible. Seismic gives you enough forewarning that you might just get that alpha into your arms or a nuked ST or just anywhere rather than that precious soft CT back armor (Anecdotal, I'm sure, but I swear the stuff is made of silk and Elmer's glue).
My thoughts on the matter, I just hope some of it is useful.