I still have a few of these engines about and intend to put a two litre in a mk 2 cortina. I have dug out an old issue of car and car conversions with an article on them . Here are a few facts about them, the block ,due to it,s compact size is very strong, the crank is steel and is tuftrided and crossdrilled. The conrods are also steel,the pistons are adequate for tuning up to 180bhp and will cope with up to 11-1 comp ratio. The cams are high lift but short duration hence the torquey nature. The heads are superbly designed and will cope with 3mm more valve lift also the ports are short with no kinks .By just bolting on a set of twin 40,s properly set up can see an increase of up to 25bhp. My mates and I all ran Supermirafiori twincams years ago . Still got one and a Mirafiorisport