Remove head studs

[3W Hank]

I had my Merc -41 block in the hot bath and I has removed studs in another 59 block after hot tank and I could then remove them ( hard hand work ) but in this California block theyiwas totally stuck.
I asked some on good chem and it was ex ’bolt blaster’ but hard to import chem to Sweden so I found a injector remover that should cure anything stucked up but how could it go when in thread rusted to one pice with bolt/block in 80 years.
-I had to usd heat and got the studs red above deck, but block hot ofcourse hot and effected by heat.
I has no experiance what this so can do to a deck and cylinder in material hardness.
Anyway I got it stand for a day and sprayed a chem a old guy made here locally, ’super lube’and yes hard work still but I could now rather easy remove 3 of them, so just pray now that non break off.

How is your experiance on this ?

Payed 1 grand for the block, import to Europe, hot tank now this so next is install one sleeve as it was sonic tested and pressuare checked.
After that I need pressuare check again myself.

Its a old weld and a new seat in that cylinder.
Look Ok and was told no issues there but… What happends when heat is on ?
It will had new caps, linebore, hone to clear rest to 1/8” ( + extra ) over then special Ross pistons so one hope it will be Ok.
I really like this Merc block as the history and I guess hard to find today. Plus it was Very nice ported way back ( seller had it for 35 years ) told it was machined in north LA.
But allot of work and money.