I disagree with the rocker cover comment.
I had an R-Reg 1998 Fiesta 1.25 Zetec-S and it had the black plastic cam cover.
Dont know if the 1.4 is different but Iwouldnt have expected so.
Basically, my main concern is that the inlet and exhaust ports are on the right sides of the engine. IIRC (and again im basing on the 1.25 Zetec-S here) that the inlet is at the front and exhaust at the rear. As long as the new engine is the same then it should be similar to the 2.0 Zetec-E upgrade in that its a nuts and bolts swap over all mounts ancillaries etc and it'll fit fine!
Hope that helps, and doesnt confuse matters further...

Paul