well my recent USACG neck and body fit beautifully until finished! They arrived a very tight and nice pressure fit but when finish went on....surgery was needed. My next build I will shave neck BEFORE finishing so it aint quite so tight.
I think any body and neck, even from the same manufacturer, could wind up needing a little massaging like a shim or something. As long as they're both set to Fender spec, they should mate as well as any two necks and bodies do.