Been there, done that…
Thankfully the block was in perfect shape and all studs removed safely.
It can be done, don’t allow others to bring you down. These cars and motors have never let me down or ceased to amaze me.
I received many replies advising to scrap the block.
I have always had old Jaguars, and lemme tell ya, the removal of core plugs for proper cleaning of block is something i will do and recommend for all future jaguar purchases despite apparent exterior condition.
It should be added i feel to the xk engine cars FAQ etc I feel so strongly about it.
If it hasn’t been done to your knowledge, it must be done as far as I am concerned.
I’m convinced as well it is the cause of unknown overheating issues and other issues caused by resulting hotspots created.
I’ve discovered all the common flushing in the world will be very misleading and make absolutely no real impact.
Despite flushing the block ad nauseum, and the water leaving the block seemingly potable…I discovered precisely same as you!
As an aside, I had never done it on past cars i hadn’t rebuilt motors on and never had overheating issues.
After this, for me, from now onwards…it is going to be fundamental in my process.
Best of luck
Kind regards