Here's how to kill To-605 "solo" w/UNACS
You can use either you and 3 UNACS (with one of the DLC that gives you extra UNAC slots) or you and another person and each of your UNACS.
Finding To-605
Start a special sortie. Choose whichever faction is in control of South Island as your preferred target. When it finds the sortie, if you see new players in your recent players tab under friends, exit the sortie and try again (you are up against humans). If the map is not Fort Denis/Inner City, exit and try again (you got the wrong region/boss).
AC Specs
L Arm Au-J-K28 (+3 power)
R Arm Au-J-K28 (+3 power)
Shoulder Muratori mdl 2
Ultimate N/A
R Bay Au-D-H23 (+3 power)
L Bay Au-D-H23 (+3 power)
Head H02 Scarlet (Linne) [TE]
Core Matsukaze mdl 3 [TE]
Arms AD-228 [TE]
Legs LeT-A-D14 [Tank]
FCS FA-215 [Quick]
Generator Makibashira mdl 3 [Cap]
Boost N/A
Recon Re-X-A07 [Hover]
Tactics
You will be facing 2 of each type I believe. I ran this with 3 UNACs, all using dual autocannons. I used HEAT cannons myself to deal with the one enemy type that was KE resistant (To-605A). I didn't even notice the other enemies as the UNACs took them out for the most part. Try to stay in the alleys somewhat so they can't charge you as easily (the To-605As like to boost charge at you and do 15k damage give or take). Hose them down with your HEAT cannons and they will die somewhat quickly. If they start to charge you try to boost out of the way. I didn't really need the extra ammo myself, so you might want to consider a CE rocket (like the Su-C-S09) instead or a CE missile (like Su-J-G27) or even a fire and forget like the (Su-J-R24A). My build did work on the 1st try, but not by a lot (was down to me at 5k health and one UNAC at 40k or so. You could also consider swapping the autocannons on one of the UNACs for HEAT cannons like your own. (Operations should be fine leaving it as is if you do this). If the To-605A and To-605S are all done, you might as well drop your heat cannons, as you will do far more damage to the To-605Ds with your gatling guns. But they've probably been killed by your UNACs by that point anyway...
UNACS
L Arm AM/ACA-218 (+3 power)
R Arm AM/ACA-218 (+3 power)
Shoulder Muratori mdl 2
Ultimate N/A
R Bay Au-D-H23 (+3 power)
L Bay Au-D-H23 (+3 power)
Head H02 Scarlet (Linne) [TE]
Core Matsukaze mdl 3 [TE]
Arms AD-228 [TE]
Legs LeT-A-D14 [Tank]
FCS FA-215 [Quick]
Generator Makibashira mdl 3 [Cap]
Boost N/A
Recon Re-X-A07 [Hover]
Here is the operation data i used for my UNACS, chip name then each parameter.
MVOR3
KD01: 5,100,15,0
RKD11: 5,100,15,0,45,5
RAIF3
R2NLC: R ARM,50,400,100,250,100,120,90,on
R2NLC: R BAY,50,400,100,250,100,120,90,on
LAIF3
L2NLC: R ARM,50,400,100,250,100,120,90,on
L2NLC: R BAY,50,400,100,250,100,120,90,on
NO SHOULDER WEAPON CHIP
REC-5
OPT33: 450,160
ACO5S: 150,200
OPTX8: 1500,16
ACOXS: 200,90
ACO8C: 50,360
TGIF3
T-DT1: 0,20
T-ET1: AC
T-FR1: INDVL
AVD-3
AHM1D: 100,60,100,3,40,front
AH1DM: 2000,60,100,5
AJ1: 40,5
EMIF5
E-T-1: 2.8,200,60
E-G-3: 5.2,50,50,4.5
E-H-1: 6.2,140,38,3
EXA-3
EXR30: 50
EXBC3: 25,100,30,3,25