Blue head Mccoy's were normally R/C engines.
Is that what you want?

De, I had rather have a C/L engine, didn't  know the difference  obliged to you...

    The only difference between the Blue Head and Red Head is the Carb and the Blue Head on the R/C version, I do believe. You need to fit a venturi and needle valve to a Blue Head, and then you have a C/L version, but as far as I know, there were no factory made Blue Head C/L versions. The head color was just a marketing thing.
    Type at you later and
     HAPPY NEW YEAR!!
      Dan McEntee

The McCoy 40 Blue Head was the same as the other 35 & 40 McCoys with a simple air bleed carburetor and an exhaust baffle that would close with the throttle body of the carb via a link.  Because of the introduction of the Hi-Low K&B fuel of the time, the end of the piston connecting rod was bushed on a few models, but not all of them. 

The bushing helped to reduce the wear on the wrist pin during low throttle operation.  This bushed Conrad would also fit in a Red Head.  For the most part, they were pretty good engines.

Mikey