Before you do anything contact your state licencing authority and find out exactly what you are allowed to do regarding engine swaps.
No - the W50 will not directly bolt up to a G series engine. You should be able to fit an 18RG to your Hilux however.
A front cut (engine / gearbox - usually auto) of a 1G-GTE/GZE can cost anywahere from $800 to $1500. You have to shop around.
Mitch.