Travel limits TAZ 3

I have a TAZ 3 that I recently replaced the bed on. They no longer make the original hardware, so I had to purchase a 12V equivalent from another manufacturer. It works fine, but it’s larger and I would like to use this extra area. When jogging the bed the Y limit stops at 275mm. I thought this might just be a limit when jogging, but it is enforced when printing too. I cannot find where in the TAZ menus to change this. It has other setting line velocity-accel limits, but nothing for travel limits. I suspect this is a firmware setting, but I am hoping that I’m missing something in the menus, pronterface or slic3r. Can any one tell me how I can change this? If it’s in firmware, how do I go about changing it?

I discover it is in firmware only. The instructions for setting the travel through M codes were not invented yet in my firmware.
I got the legacy Arduino IDE 1.0.5-r2 compiler here: Google Code Archive - Long-term storage for Google Code Project Hosting.

I got the TAZ firmware source here: Index of /TAZ/2.1/software/2013Q4/firmware/marlin_taz

The ArduinoAddons library is important for missing libraries.

Modified Y_MAX_POS in Configuration.h from 275 to 300

Compiled for Mega 2560.

Uploaded and tested jogging. Seems to have worked. I have not printed yet though.