Not sure where would be the best place to go, I suppose it depends where you are based. I've never had any major mods like that done but I'm sure the likes of Dizzie etc who have could recommend a few places.
As for doing it yourself, I suppose the initial transplant, cabling up, fuel system fitting etc would be simple enough as long as you are handy with a spanner, have the tools and have a decent indoor workshop (something I would love to have).
I think the difficult bit comes when you have to build some suitable driveshafts, hook up the clutch, find a suitable exhaust and all those type of things.