I am thinking about changing the engine from the 2ltr pinto to a 2ltr zetec, will there be much difference in power wise? ,i will be fitting the standard injection equiptment.

You should be looking at approx 130-140 bhp on standard ford gear. 160+ on individual throttlebodies

Also worth considering the Toyota option

Not a major increase in power but a lot smoother with 7000rpm a safe rev limit, 7500 if need be using standard kit. Big advantage is if you go for Webers or throttle bodies and 165bhp on standard engine with 200bhp with head cams, again with standard bottom end.
Another big advantage is the number around which can be fitted with no need to recondition, just fit and forget.

As stated above, plus it is said to be lighter (ali head I imagine) that the old boat anchor and I would think a bit smaller as I am sure I read somewhere it was based on the BDA block?
It is a more modern engine with much tighter production tolerances and, again as sated above, just look at the number of Ford cars fitted with them.