After I ordered my 131 kit and found out it was back ordered I checked on the 131 crate engine. My dealer was taking my stock engine on trade and the OTD difference was less than a $500. There are several parts you have to buy with the crate that comes in the kit, like the head pipe. That alone is about $700. Biggest issue is it is not available in Granite to match the other parts of your bike.
Unlike the 120R and 120ST when you get the crate the dealer sends HD your VIN number and they stamp the engine to match your bike so it is just like it came that way from the factory.
Before you put your money down on the kit check availability. I ordered mine in mid-February and it took about 60 days to arrive. HD had over 1,500 back orders at one point.
Enjoy your new bike.