[Troutman]

Originally Posted by Meir

if you are still looking for a good solution to drill a center hole, this one works great:

https://www.youtube.com/watch?v=RbDF9P1uDyk

https://www.yourstoreonline.net/4-piece-metric-quick-center-drill-out-kit/id1136771/product.html

That is a great solution although not available in the UK and import/postage would make it too expensive..I am getting something similar made to screw on the broken studs, it'll have a 3mm hole drilled right through. Cost £7.
I ordered some PBB which again is not easily available in the UK . cost me £12 ($15) for a can. I read somewhere it's better than WD40 for penetrating the threads. They key here is to make sure you clean off all the corrosion where the stud enters the head to allow oil to go in. I'm going to heat them up too which might help draw it in.