Mine is cracked in the same place, not being one to tackle fibreglass, I made a new mount that would spread the load better and also installed an 'ultimate engine steady' from a mini on the thermostat mounting.
I believe my engine also has a rear-ward facing gearbox mount (but if i remember correctly weirdly no forward mount...), I intend to add another gearbox mount, plus look into having a thicker piece of metal fabricated for better load bearing!