For an XE or LET conversion, you'll need to find yourself a bigwing manta 1800 sump and pickup,and preferably the alloy engine mounts as well.
Most folk use the manta 1800 box (getrag) , as its an easier fit, although if you want to do the type 9 conversion or the carlton/ omega route, you can with an adaptor, but it makes the box a bit longer and you need to look at handbrake /gearstick relocation and reforming the gear tunnel etc.
A fair bit of work, but ok if youve got time and a big heart!
Also dont forget, you need to look at , bigger brakes / suspension upgrade / rear axle and a fabricated propshaft as well, to name but a few other areas you need to consider for a conversion.
Good luck!