Hi Alga,
The picture looks like a Dunnell engine or similar, they use a special sump casting to mount the alternator on.
The four bolt holes you refer to are an ideal engine mounting point.
I would mount the alternator under the front carb, above the oil filter. You can still drive it with a single belt and use the alternator as the belt tensioner so you won't need any extra pulley's plus you will have more 'wrap' of the belt around the crank pulley. There's only a 1/4 of the belt wrapping round the one in the picture so it's likely to slip when the alternator is loaded.
You'll need a silver top Zetec and an Escort water pump which turns the same direction as the crank pulley (Mondeo water pump turns opposite direction as it's driven off the back of the belt as are all black top zetecs)
HTH BV