Steve, What are you using to cover the Cub?  I have noticed that "Cub Yellow" comes in many shades as I try to match up covering with paint put on my cowl and landing gear on the GP Cub J-3 I am building.  I am about the same stage you are, except that I don't have any covering done as I am trying to decide on fabric or film for covering and hence the matching colors issue.  ;-)

I am powering my Cub with an O.S. .91, 4 stroke that I bought sometime in the 1990's and never completed the Mustang I was going to put it in.  Sounds like we exhibit some of the same symptoms of buildus interruptus when it comes to plane projects.  ;-)</p>