For a buggy like that a nice .21 would probably be better for it. I've drivin buggies with big engines and ones with nice .21s and the nice .21s are jsut a blast to drive.
If your trying to save on cash, a good one to look at is the Collari B3. Its a 3-port .21 that is Italian. Because its a 3 port its got some decent torque. If you want you could go with the Collari B7, which has some more top end to it than the B3.
These engines have proven to be reliable for me, and aren't too hard to tune. I've gotten some dirt in my dads B3, cleaned it out and it still runs great to this day. I am very impressed for what I payed for it. They go for $170ish now.
For $250 you may be able to find a Novarossi P5X. I would not suggest this as a basher engine, but it is an amazing engine, very good torque and revvs quite high too. Its very tight, so its hard to break in, and can be trickier than the B3 to tune, its more of a race motor, the B3 is easier to deal with every day.