Buggy advice needed

Just having stepped into the Brushless world with an 3905 E-maxx, mainly for my 4 year old son, I have been looking around trying to figure out what a good candidate for a buggy conversion might be. The E-maxx is in a 75% finished upgrade state and I need a project for when I get done and something that can keep up with his little monster (1515 1Y/F, Quark, Fastlane). He is becoming a great little driver. Thanks to this thread, the E-maxx is becoming a serious toy... $$$. It never ends does it...

It will be for bashing only, as we aren't into racing yet. Eventually I would like to get him driving the buggy, then when he gets a little better we can upgrade to something modern and go race. So I was thinking an older Ofna Jammin would fit the bill. Maybe something even older than that... it doesn't need to be competitive. I am kind of leaning towards Ofna, no reason really, they just look like they are quality pieces. I don't want to shell out the money for an 8ight since I am not racing it. There are so many buggies out there (new and old) I am a little lost with the differences. I have never even looked at buggies until a week ago. Upgradable parts availability would be key.

I have a Neu 1515 2.5D for it. Suggestions? Anyone have a conversion they want to sell?