Frankly I would go with the YS.

The YS is a supercharged engine, while the O.S. is not.

As such your YS will produce about the same power as the O.S., but be lighter and smaller.

Make sure you get help tuning the engine since this is your first four stroker.

Also I find it easier to break an engine in with a heavier/mass prop, such as an APC.