SSRM without BAP...well at least there are other weapons. UAC5 is great, but remember there is a chance for them to jam. the MLas maybe your only weapon when you are in a tight place. I suggest lowering the engine rating to either hold a BAP, or switch them streaks to 2xSRM4, or upgrade the MLas to LLas.
My variation. I move the streak ammo to the head also, this way the UAC5 ammo in the torso would be used first, reducing ammo explosion chances. Also, Bap.
I don't think this version has to move that fast. Traveling 75 kps should be be sufficient, so there are another 1.5 tons to use when downsizing to an XL 255. I'd rather like more ammo for the DUACs, as those are the main weapons by a wide margin, and would also prefer more protection for the ammo-filled legs. You could even be cheap and use the stock engine. This would put the build firmly into a mixed fire-support & bodyguard playstyle, but there's nothing wrong about that, is it?