I would like to know more about both configurations. O0 }:)
For the dual UAC/5 dual AC/5 fitting, I can't recall exactly how it was configured aside from the fact that it had a UAC/5 and an AC/5 in each arm, had an XL engine that maxed at 39.5kph before speed tweak, had two double heat sinks in each torso (total of 10 DHS), no CASE, and no endo-steel. To make everything fit, I had to thin the armor on the legs and the arms somewhat, probably dropping one or two tons of armor. As far as ammo, I think I had...3 or 4 tons of AC/5 ammo, and 5 or 6 tons of UAC/5 ammo (ammo was shoehorned in wherever I could fit it).
Because it was so slow, this build had trouble bringing enemies to action and was very vulnerable to enemy fire. However, on those occasions where it could get an enemy in range it dished out massive damage.
For the latter build, it's pretty much as described. Locations of equipment were as follows: 2 med lasers in the CT, 1 DHS in each torso (total: 10), CASE in each torso, 1 AC/5 and 1 AC/2 in each arm, 2 tons of AC/5 ammo in each arm, 2 tons of AC/2 ammo in the right arm, and 1 ton of AC/2 ammo in the left. Endo-steel locations are auto-allocated, and armor is half a ton less than max, taken from the legs.
Speed for this maxes at 54.3kph with speed tweak, IIRC, which is a marked improvement over the other fit. That said, I believe there are enough free slots to swap to an XL engine if you're willing to sacrifice survivability for speed. If you go XL, drop the CASE as it won't provide any benefit.
EDIT: There are enough slots and tonnage to fit an XL 255, the largest engine the chassis will take. This should allow you to move 1 DHS into the engine and remove the CASE. This will leave you with 4 extra tons to play with, which you can use to fit BAP, AMS and 1 ton of AMS ammo if you want. Alternately, you can just throw in more autocannon ammo. For an even more radical shift, that extra tonnage will allow you to update the AC/2's to AC/5's. You'll lose some range and will have to manually manage your fire (i.e. use multiple weapons groups and stagger your first shots) if you want to cause continuous impacts that make it hard for your opponent to fire back, but it will increase the single-volley impact to match an AC/20...that fires much faster.