If you have "space" around the Keggerator you should be fine...
It need to breathe... the more the better, a very small fan would be ok as long as this room does not get really hot.
I would say a minumum of at least 3 inches on the sides and the back to be safe but since you say you also have room on the top I think this sounds good.
My question is how is the Tap going to get through the bar?
Are you going to drill a big hole, remove the tap, put it through the hole and reassemble the keggerator?