I popped them in, A on bottom, B on top, with the chips to the right most side.
At first it only booted to a black screen, I then turned it off and on again, booted all the way but my serial mouse would not work anymore.
Turned off again, soft booted etc. Same thing, no mouse.
Put 3.0 roms back in, now it keeps doing the same thing, but occasionally if I softboot, the serial mouse will work, but not all the time like it used to...
EDIT
If I boot up and the mouse does not work with the 3.0 roms, I just unplug the serial mouse, plug it back in and then it works all of a sudden, will test with 3.1 roms.
...and that works too, same thing though, I wonder why the serial port is suddenly acting up.
Anyhow WorkBench says I have Kickstart 40.68 so I assume that maybe there is nothing wrong with this set, and that they only needed to update one of the two chips?