Newbie needs help!

You've probably seen that title before!
I have a rhino but I need some Grizzly expertise! I needed a head for my 660 and new ones are very pricey so I found a used one off a Grizzly that worked fine. The help I need is finding out what the two bolt holes in the rear of the head, just below the cap and above the exhaust ports are for. I think they are 12 mm and also think exhaust blows out of them with the two exhaust tubes bolted up. When I got the engine finished and turned it over I put my fingers by the holes and am pretty sure exhaust puffed out, am not able to check further as I had to leave home right then and won't be back for 4 weeks. I've looked at head diagrams and don't see anything on it. The bad thing is I promised my wife I would have it finished so she could use it while I am gone but told her to leave it parked as I don't want her to get carbon monoxide poisoning. Any help would be very very much appreciated.