Smotherman is a rough in a lot of cases.
But if I use it the Custodian comes at 328,5pts including 5pts per grav hook.
Drop 5% for boarding -16,25pts
The TS system is on ship self 20pts:
turrets have a re-roll option so gain, so 6x5pts instead of 4x5pts (=10pts more)
railguns count above 45cm as more railguns to count, under 30cm this does not.
So: 16 basis weapon batteries equals 12railguns without right shift @45cm (look it up in the table)
16wb @45cm = 48pts. But the bonus is dropped under 30cm so 12 gets worse under 30cm and is the same as 16 regular above 30cm
(sounds jibberish but its true
)
Downgrade the 48pts to max of 45pts. That is 9pts more then what 12wb @ 45cm cost...
...
thus.... TS = +10pts for turrets & +10pts for railguns.
328 (base)+20(ts)-16 (boarding)= 332pts
Furthermore: above is counted with full 32,5pts for Imperial Prow:
a) Tau prow deflector can be destroyed / IN not
b) the IN prow is overcosted anyway in smotherman
So drop those 332 to 325 pts.
Now the most tricky part:
the range of the tracking systems. It can be good, it can be not.
10pts would seem okay for the range. (So in total the Custodian pays 30pts for the TS)
So we end at 335pts.
Undercosted vessel? Nah.
edit: resilient bombers: T-hawk bays cost 10pts according smothy, I used 13,5 IN value.