Nothing you'll find is aircooled specific... Even my Ricardo software lacks some features that would optimize it for aircooled engines, or HO engines.
I tend to favor Dynomation and engine Analyzer pro for engine design. typically we will use features from each of these in the design of a single engine as each has characteritics that are better than the other.
I like EA pro for it's 3D cylinder/ piston modeling as it is very beneficial when designing pistons and calculating valve relief depths for certain combinations before the engine is mocked up. I tend to like dynomation for it's camshaft iterrator and camshaft library that integrates with my Audie technologies Cam Pro Plus. This way I can profile a cam and spit the info directly into the library. The same goes for our flowquik software by Audie, it exports directly into dynomation as well..
I have consistently seen the most accurate numbers from dynomation than any other software, but I don't typically model the engines to see the outputs, more the efficiency and RPM ranges that can be experienced with various camshafts and port arrangements