my 8ight-e convert open to sugestion...

[DRIFT_BUGGY]

2 most common diff fluid setups in the 8ight is 7/10/3 or 5/10/2.
The Losi BL Kit is a good kit for the price. Should look at getting a Kyosho Nylon Gear as the Losi metal one would be pretty loud. You will have to run the 44T Kyosho Spur ( http://www.rc-monster.com/proddetail.php?prod=KYOIF147 ) as you would have to run spacers under the diff mounts to be able to use the 46T Kyosho Gear. But if the noise of metal to metal doesn't bother you than you can just keep the standard 45T spur.
Any reason why you want to run a 1515? Most usually run a 1512 in a buggy. Tekno/Impakt have the new 1512 Sealed Cans coming out very soon (maybe 1 - 3 weeks)
Not sure on the height difference between the Losi and MMM esc but the ESC mount is behind the battery tray on the Losi kit. I think the MMM would probably hit the body so you may need the 8-E body LOSA8097. Someone who has the Losi kit and MMM esc maybe able to confirm this though.