Hey Ben, sorry it took so long to get back to you. I wanted to take pictures of me doing my Prestige neck (7 string) into non-prestige body (OOTS swirl), but time has not allowed me to do that yet.
What you need to do first is to get VERY accurate measurements of both the heel of your neck and the pocket in the body....right now were only concerned with the width of the pieces. If you have a metric caliper, that would be the best tool to use.
This is a metric caliper:
the caliper does not have to be metal...... but it DOES have to be accurate.
These are the places you want to measure:
If there is paint on the sides of the body cavity, you'll want to sand that away first......if not, get the measurements now.
Your also going to want a metal ruler that has millimeters clearly marked.
I use one that has a cork bottom to avoid unwanted scratches.
You'll use this ruler during the sanding process, so I highly suggest finding one.
When you have you measurements, please post back and we'll go to the next step.