Farmall Cub

I purchased a 12hp AQS engine to replace my 10hp AQS with a air vent hole in the block(thrown rod). I just replaced the head and head gasket and the engine is in new condition. It looks like it has no hours on it. The valves are snug in the guides and the seats look great. The piston has no play in any direction at all nada. First its a 1200 quiet line with the AQS engine with that exhaust box that the muffler box attaches too it. I bolt it all up and it keeps on comming loose. I see that long 3/8"-16 threaded stud sticking above the engines head and there what appears to be two threaded holes in the adapter plate/housing that bolts to the block. I been thinking a y shaped bracket with three holes in it would allow the adapter box to be held much tighter than the orginal setup. I been also wondering because the holes are there if i maybe missing this bracket it once had?? Maybe?? This is the only problem i have left on it. Bill

BTW; I never replaced this headgasket and it was blown up thru a head bolt hole. I guess the head bolts were a tad loose. The new head with the cadet gasket is torqued now and i tripple checked it at 30ft lbs. I'll run it and do a retorque next.