As Steve say's as long as your chassis has the "cruciform" front end, you can do it either way.
There are two schools of thought on this, IMHO it is much easier to do it with the engine and gearbox intact, took mine out and put it back in on my own last week. easy peasy
As Doug says, get the front of the engine as high as you can and at a steep angle, I use a LOAD LEVELLER.
Guy S B Lowe o *arrowup*o
ZETEC Conversion here