I'm not so sure that head will fit. Just because the two engines have the same .18 displacement does not mean that the heads are interchangeable. The cylinder diameters can be quite different between two .18's. I would be really surprised if it did fit. And even if it appears to fit, it still may not be a perfect match, and the motor may never run right, if at all.

My advice would be to stick with the stock head, or buy one specifically made for the engine. Save yourself the headache. (pun intended)