200 true watts would be perfect. True watts meaning actual power draw, so for a LED you’d want something like a 400W equivalent, but all manufacturers I’ve seen will list actual power draw in their specs.
As far as exhaust is concerned you don’t need much with the cubic footage you have so I would get a 4inch inline fan and a small carbon filter
Fan should have speed controller and go with something like a 100cfm range that would exchange air 4 times a min in you set up which is why you’ll need a fan control to slow it down a bit
Happy growing CB