Hard time with front engine mounts for alignment

[yannickevenas]

Hello,
1987 OMC cobra 5.7 on Bayliner contessa here.
I'm trying to do the engine alignment after replacing the gimbal bearing and I am having a hard time.
The mount bolts are rusted. I tried WD40, tried to soak the bolts in vinegar to get the rust out, tried a cheapo impact wrench, breaker bar, no luck.
I will try a stronger impact in a couple of days.
Should applying heat help? I've never messed with the engine mounts before.
I'm running different scenarios in my head. One of them is supporting the engine from above, cut the bolts and replacing them, but that's if I can remove the 2 bolts from the base..
Oh lawd.
Any other suggestion to get the rusted nuts out?

 

[Scott Danforth]

Spend $70 on a pair of new mounts

 

[yannickevenas]

Well, the more powerful impact tool rounded the bolt. FML.
The socket sized I used was 15/16. Isn’t it the right size socket?

 

[Bondo]

One of them is supporting the engine from above, cut the bolts and replacing them, but that's if I can remove the 2 bolts from the base..
Oh lawd.

Ayuh,...... If you can get the bolts outa the block,......

The bolts into the hull, should be lag bolts,....

 

[yannickevenas]

Yeah that’s my next step. Trying to figure out now how to support the engine. Either from the top or the bottom.

 

[yannickevenas]

Update:
I was able to remove one side, cut the bolt and refurbished the mount.
I replaced the rusted lag bolts with stainless steel.
I couldn't find any SS in 5/8" at the local stores, so I used galvanized bolt and nuts for the adjuster.