I just ran a short section of hose with fittings from the bottom forward edge of my 1100 into the bottom edge (former fill) of my stock 650. Then I capped the overflow of my 1100 and re-routed the boats overflow into the stock 650. You'll have to watch the 650 though as it will push your seats up if you wait until the overflow starts to run out the Side of the boat. It took me a few fills to bleed all of the air out of the bags too since the 650's are too big for that space. Just make sure the bags are oriented with a plug in an accessible spot before you start to fill them.
2013 Mojo