Motor mounts....

Not sure whether to post this here or in the REPAIR section.   For those following, I've recently purchased a new prop, shaft, coupler, etc. Started simply enough with replacing the cutless bearing and cascaded very quickly into all of that. Now with all the parts in and the bearing replaced I continued with the shaft installation and alignment. And naturally that now has opened another door as the alignment is WAY off -- I'm not even going to quote thousandths of inch dimensions here. it's a large number.   The rear mounts need to be lowered nearly 1/8" and to port slightly.

Here is the rub: All 4 of the mounts are frozen fast, rusted solid.   I've spent the last 3 days soaking them with PB, oil and such, torquing them frequently trying to free them without success. I finally thought I had one broken free, but turns out the lower nut had just rounded over.   

At this point I'm guessing I have no option but to pull all the mounts and replace them, unless someone here has an innovative way to break them free without breaking them.

could try a bit of heat I guess ?