the crank is different on std NA efi engines such as the xr2i, not by much though, the frst has a throw of 79.5mm xr2i has a throw of 79mm.
blocks are the same apart form the oil return, but as above, you cun put one in the sump, just dont put it too low, you dont want it under the oil level.
where to put it depends if you got T2 or T3, but for what you plan im gussing your after big power meaning a T3 will prob be fitted, if thats the case you have more room for the return.

efi heads are the same inc the cam, i belive the valve springs are rated different for a turbo modle, but there like £4 each or something from fords so no biggy.

choose a cam wisely, i had a kent cam that didnt even make 1200 miles before it was completely fucked, and that was on a freshly rebuilt engine.

if you want massive power, i would say go zetec from the start, the cvh is a good engine and good power can be got with time and money, but lets face it, its had its day compaired to newer engines, i sometimes wish now i stuck to my plan when i restored my rs and went zetec rather than rebuilding the cvh