When you replaced the gaskets, did you check to make sure the cyl studs were all tight into the case? They can back out of the cases and if they become loose, it will cause a base gasket leak. If loose, remove from case, clean threads, place a drop of RED locktite on threads, then tighten into case.
Also, when doing your cyl head torque..make sure your following the correct sequence and rather than the 10 ft lbs, 20 ft lbs then 90*...go 10, 20 then 40 ft lbs. of final torque. This method is more accurate than the 90* and you will be less apt to have a leak.
Also like others have said, make sure you let the motor warm up before beating on it.