Grumpy luckily I managed to pick up a few scrap engines so I have 3 spare bosses now for zero cost - so thats a plus.

I did however follow your instructions very carefully with the ezy out and the bolts really are stuck solid. I soaked them for quite a few days and no movement at all.

For now its no problem as I have a few spare rover boss's.

I appreciate the advice regarding not compromising the boss's structural integrity. That is specifically what I was after.
Peter