rsheve

I am looking for some help with my 2015 Massimo 500 EFI.   I just picked it up recently and trying to work on a few issues.  I think I may have a head gasket that is failing.  I am constantly filling coolant and not seeing any leaks.  Looking to replace with a Yamaha head gasket.  Does anyone have the part number or can point me to how I can cross reference one that will fit?