Well now, even with the exhaust port opened up it's not as big as a stock Wild Thing port with that steel insert in it. It's gonna be hard to make up for that plus the larger displacement with an air filter! That 42cc Poulan engine actually makes quite good power with a muffler mod.
Seriously though, I ran a Craftsman version of the Wild Thing for years and now have a 1998 A/V version I just put a chromed Poulan Pro PP260 engine into. So if you were to compare a PP260 to the Earthquake G3800 clone they both have good A/V and chrome cylinders. The Earthquake is lighter, narrower and has an adjustable oiler (who cares really in a saw this size - I'll never touch it).
The Earthquake has a 2-piece metal (probably aluminum) chassis while the PP260 is plastic, but both are strong. The PP260 is going to make more power.
As far as manufacturing, the PP260 is higher quality parts and made in US and a Wild Thing would be too, plus you get a supply of parts. And a new Wild Thing would have a strato engine for lower fuel use and less exhaust crap to breath.
I do like running both saws. With the Earthquake ported and the base gasket removed and muffler modded it's pretty snotty actually, while still light and well balanced like the G3800 original. It's the same basic chassis as my McCulloch MS4018 (GZ4000) 40cc strato saw which is a far better comparison to my 42cc Craftsman/Poulan. Both are muffler modded with stock engines. I'm running the McCulloch most now because of the lower fuel use and emissions, but the older Poulan has more power - it always starts and runs well, it has a large fuel tank and it just works.