More photos:
The top of the head, after the rockers have been removed: (One head bolt undid from the bottom, and the brass acorn-type nut is still on. You can see it in the bottom, at around the 7-o'clock position)
URL of the original image: http://www.aussieheavyhorses.com/ASSETS/Fiat-50L-55L-crawler/Fiat50-engine-block-DSCF4456_Vga.JPGOne of the two typical head bolts that broke - corroded in the lower end (The top-end acorn nut is still stuck on):
URL of the original image: http://www.aussieheavyhorses.com/ASSETS/Fiat-50L-55L-crawler/Fiat50-engine-block-DSCF4467_Vga.JPGA close-up of the 'cylinder' of two cylinders, also showing the muck of the water jacket & two head bolts, still intact:
URL of the original image: http://www.aussieheavyhorses.com/ASSETS/Fiat-50L-55L-crawler/Fiat50-engine-block-DSCF4470_Vga.JPGAs above, looking deeper down into the bottom:
URL of the original image: http://www.aussieheavyhorses.com/ASSETS/Fiat-50L-55L-crawler/Fiat50-engine-block-DSCF4479_Vga.JPGThe two head bolts that broke/sheared off are the two diagonally opposite corner ones upper left & lower right, or front right, and rear leftmost,
and the one that undid from the bottom, is, in this picture just above cylinders 3 & 4 (right side)
URL of the original image: http://www.aussieheavyhorses.com/ASSETS/Fiat-50L-55L-crawler/Fiat50-engine-block-DSCF4451_Vga.JPGThe bolts do come right down to the sump area, so maybe remving the crank shaft, and pistons/conrods, and then using an EZE-out or something from underneath might be the answer? I can't see drilling down from on top or welding something onto the remnants of the stud on the topside, down in the 'dungeons' near the cylinder/sleeve bases is going to be easy or a good weld, but I may be wrong...
I'd like to get them all out & replace the lot though, even if we have to machine something up from a long HT bolt.
(Are head bolts likely to be some superspecial high tensile substance, or a relatively common HT steel, do you know?)