You're gonna get alot of different opinions here but here goes...
First of all, 4" of lift on a YJ will clear 33's. I'd recommend a 33x10.50x15 or a 32x12.50x15 because of the 4 banger, as the 33x12.50x15's that are more common will certainly be a strain on the 4 cyl. The 33x10.50's would be lighter and have less wind and rolling resistance, and in my opinion they look better on the SWB Jeep.
If you get wheels, I would recommend something with around 4 to 4.5" of backspacing. If you want to use the stock 15x7" wheels, you can run the 33x10.50's with merely adjusting your steering stops (5 minute mod) as the factory backspacing is 5.25". Going more that 4" BS will have the tires sticking out past your flares and will rub the flares when you flex the suspension. TJ flares or wider flares will remedy this but you won't have to worry about it if you get the backspacing right.
As for the tires, BFG makes both the AT and the MT in a 33x10.50. I would get the MT's if you like to play in the mud alot (speaking from personal experience here). Also, Interco Super Swamper TSL radials come in that size and if you don't mind a little quicker tire wear and don't do alot of highway driving they are a great choice for the trail. If you are set on the MT Claws, they perform great offroad but like the Swampers they have been known to wear quick if they see alot of pavement time. The Claws don't come in a narrower 33 so thay may be a factor too.
I'm not saying you can't run a 33x12.50 on the 4 cyl, but expect to lose 5th gear and big hills will be embarrassing. The 4.0 with the 4.10 gears that came stock in your 4 cyl will make this alot better of a setup.
Hope this helps.