Supercharging a 5.4?
 

I was thinking about spending the year junkyard building a 5.4 (or more) then supercharging but is it is easy as adding spacers to a 4.6 bracket or do I need to custom mill one? What other custom things are involved? Is there any way to keep the swap california legal?

You are better off finding a 5.4 from a f150 or other ford truck. I don't think you can enlarge a 4.6 into a 5.4 I could be wrong though.

Thats what I meant by junkyard building one, finding one in a junkyard. I know I can stroke a 4.6 to 5.4 but it still has the shallow deck height and it is at its limit and cant make the same power.

If you can find a solid 5.4 and you manage to put together a lightening supercharger kit then you can do it. It's been done before. Check the 5.4 swap thread it's really long but there is good information in there and you should be able to get your questions answered.