Not a bad idea but it looks like that housing is threaded tooWhy not remove the other two bolts and see what you are left with. I would think since the head has been flattened the housing should come off. I don't recall if the housing itself is threaded. Does the replacement bolts have threads all the way up the shaft? They are aluminum bolts as I recall. They can easily be drilled out.
Good pointTake a look into the flange hole where one of the other bolts has been removed. You won't find threads in the flange regardless of the image above. The 3 threaded holes in the flange picture above must be for some other part to bolt to this housing not for the housing to bolt to the engine. Again, you can't have threads in 2 separate pieces that bolt together. they would never pull together by tightening the bolt.
No threads on the #1 side so it would pull away cleanly. Murky waters here tho, you risk damaging a cylinder head. Curious why OP's guy grounded down the threads of that bolt in pic 2. post #1 ?View attachment 1076947
number 1 side is not threaded. Number 2 side is. If you did cut the head off the bolt I would think once the other two screws are removed it should come off. Unless the number 1 side has threads which the prior poster says it doesn’t.