270 sounds about right. Look on the tag, it usually gives clutch pressure.
If regulator was stuck, clutch pressure would be sky-high, until something broke.
Also, pressure would not be constant with changing rpm if reg was sticky. It would go low with low rpm, high with high rpm.
Seen some TD gears where port and stbd ran at different pressures (by design) due to the different clutches in action.
You need to do a little more sniffing around. First is read tags. Next swap the test gauge to the other gear.