We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common ! Just start by posting a note introducing yourself to the group, that's all it takes here (we don't ask for or retain any personal information here, because our intention is to just "have fun and share information".
I think you will find a wealth of information here. XK-19 is a very nice boat. I think it came with a 350 F (GM 5.7 l) and a Volvo 270 or 280 outdrive originally. I don't know much about OMC but I'm pretty sure they did not make the engine itself - just the outdrive and other bolt on parts. You don't say if it's a V8 (I cannot find information on the model you have listed) but if it is it could already be a GM 5.7 with OMC parts instead of Chris craft (exhaust manifolds , cooling system etc). Gauges are almost always made by third party's so I would venture to say - yes - you should be able to make Chris Craft gauges work with the OMC Engine. Good luck with the purchase and keep us posted.