engine mount bolts

work started on our little project recently and we got to starting the engine mount problem today, when we removed the old snapped bolts we descovered that when the bolts were replaced last time there was only about 1/2 inch of thread in the block.

i know what i think but does anyone think this might be why they snapped this time??

its also annoying that i called vauxhall and asked what bolts were needed and the bolts they told me were about 40mm too short, luckily the longer of the two is perfect as the short bolt and the longer one needs to be about 30mm to 40mm longer for it to fit.