So not an ideal load out to be sure, but, I came up with this one when I was trying to find a use for "lesser" weapons.
Situation, its 3049 & your employer has been "gracious" enough to "gift" you with an Ultra-AC5 & several pallets of ammo.
What mech do you equip it on?
My top 2 choices for field refits of a single gun like that were Shadow Hawk & Zeus, and this is what I did with the Hawk.
The size of the UAC means it has to be C-Grade, so as long as I had to use a repair bay, I also tweaked the HS/Armor as well.
Remove AC5 - Add UAC5
Remove SRM2 - Add ML
Remove 1 HS - Add 16 points of Standard Armor.
The 11 remaining SHS is still enough to do a full Jump & Alpha the 3 close range guns which is more than you can ask for.
The extra armor, removal of SRM ammo, & increased rate of AC ammo usage means the "ticking timebomb" aspect of the mech isn't quite so bad.
Downside is, it looses the specialty ammo aspect for all but the LRMs
I call it the Shadowhawk-2U
Note: This refit also works well if its a UAC5-prototype in the 3039 timeframe.