Interesting Chassis. I looked for the dual battery Ripper chassis but did not find anything like yours. You could mount the battery on the bottom by mounting a battery plate going the length of the chassis. There should be room or find a 2s lipo that will fit the current battery slots.
Those Orion motors should work good, but may not last long on a 2s lipo. The LRP motors I believe are 80T and the reason your not getting any wheel speed. I linked a Clod buster common electronics set-up for your viewing from Clodtalk, RC10talks sister site. It should help you determine brushed versus brushless.
Also, Brad the owner of TTR is on Clodtalk and should be able to identify the correct name for that chassis and give you more battery placement options.
If it were mine, I would run one EVX-2 with Traxxas Titan motors from the E-Revo (Rear motor is in the proper reverse rotation) if their is room for the motors. Sometimes the longer can of the Titans hits the lower links.
One thing I see when looking at the shocks, is they look too long or in the wrong position on the lower links, which is why your axles are clocked. The upper links should be more parallel to the ground helping with the COG which creates the chassis sitting too high. Lowering it would help lengthening your wheel base too for more stability.
http://www.clodtalk.com/viewtopic.php?f=52&t=26702
I Hope this helps.
