VR 5ltr into UC sedan

I'm interested in fitting a VR 5ltr engine/box into my UC.

How difficult is this? I anticipate that the gearbox could be the difficult part for some reason...?

Also, where/who in Brisbane could I get to do the conversion? I've become slack in my recent years and just want to get the UC on the road asap with a V8 in it

Thanks in advance.