Hi and welcome.

I don't have an SV-7 kit but some things are fairly universal.

How much of a gap do you have? With a bolt-on, you don't need the pocket to be particularly tight, especially when the neck is unfinished. Adding finish on the neck will obviously make it wider, and the more finish you apply, the wider it gets. So a very tight neck pocket to start with isn't a good thing with a bolt-on (though good for a set neck guitar). So it then comes down to how much of a gap is there?

As the design has no rear to the neck pocket, you will be 100% reliant on the screws holding the neck in place, which means that you want them to be able to pull the neck right down to the body. To be able to do this, you'll probably need to drill out the body holes for the neck screws so they are the same width as the screws. You don't want the screws biting into the body wood otherwise it's possible for the screw heads to be pulled against the body before the screws have fully pulled the neck against the body, resulting in a gap which you can't close because the screws won't turn any further. If you're not quite sure which size drill to use, drill some test holes in some scrap wood and pick the size that just allows the screw to drop through without any excess side to side wiggle.

As for the neck position, I'd have it so the end of the neck sits level with the wood either side of the neck end of the neck pickup pocket. You don't want it protruding into the pocket, and you don't want it any further forward, otherwise you'll leave gap between the pickup and the end of the neck.

You've got a 25.5" scale length (647.7mm) which should be the nominal vibrating string length, So the fretboard side of the locking nut to the point at which the string will just leave the saddle on the FR. Measure from the high E string nut position to the high E saddle (not the easiest of things to do without the FR fully fitted). Best to put some masking tape on the body so you can mark the saddle position and then measure to that rather than try and balance everything yourself. Use a metal ruler rather than a flexible tape measure for better accuracy.

I don't know how the FR come set up WRT the default saddle position, but for scale length measurement, you want them pretty much all the way forwards. The intonated position will always be a slightly longer length from the nut than the scale length (there's a transition section of the string from vibrating to not vibrating which requires slightly ore length, plus extra tension from fretting the string at the 12th fret makes the string sharp if set to exactly the scale length). So intonated lengths are probably from 0.5-1.0mm longer on the top E to 3-4mm longer on the low B. This will vary with string gauge and string material. But for checking scale length, it's easiest to use just the top/high E string position. As long as you have the ability to move teh saddles back by those sorts of amounts, you should be fine.

I'd hope that the kit is designed so the end of the neck being level with the pickup pocket walls works. There are photos of the 6-string version, the SV-1,in the photo gallery section of the forum https://www.buildyourownguitar.com.a...ead.php?t=6499 and they all seem to have the neck in the position I've described.