Tom & Joyce:
I would look at DEKA AGM GP 31 and replace my 27s with these. They are nearly exactly the same size but 6 lbs heavier. They will give you 105 Ahr vs 92 Ahrs for the 27. You can get these Deka batteries shipped anywhere for free from
tristatebattery.com/
Also, you can read all about these batteries from the Deka East Penn plant here:
www.dekabatteries.com/assets/base/0245.pdf
So, YES...go with GP 31 and they should fit the same place your 27 are!
Here is screen capture of the key data, but see the PDF above for more.
Click image to blow this up...
Hayden