Can someone fix my guitar neck/head transition step file

Done with loft feature

You can use fillet Feature for simplicity.
If you are not happy with the result, try to use loft Feature.
Blending 2 complicated faces always works better with loft.

Thank you, could you take a look. Step file attached. Needs a lot of work.

Wow, thank you very much. When I first opened it in Solidworks, before you worked on it, it had a lot of gapping and face problems that wouldn't go away. I figured that was why my loft didn't work.