It already comes with a vauxhall engine... 1057cc and you can do a straight swap (almost) with a 1256cc one.... OFF THE SHELF nothing else will fit, it will all have to be custom made, if you good with a welder then making engine mounts etc shouldn't be to much of an issue
Question whats wrong wi the present engine that makes you in your first post ask to change it? Maybe tell us about the car, you and obviously the dreams you had upon buying it