A while back I bought a Delta Grooves neck because, new to guitar building, I wanted to see how nice a neck could be. I finally put this into a nice Tabak box. Humbucker pickups, enclosed tuners, hardtail bridge.
The intonation is so whacked I gotta move the bridge back further. The sustain on this neck is beautiful. The humbucker is warm and gnarly with gain applied. As soon as I get the intonation fixed, I'll put a sound bite up!
You seem to be winning Richard, but that lack of further travel is going to restrict your chances of intonation a bit, but if you shorten the spring a bit, it looks like you can get another 4-5 mm, and that will get you pretty close i'd think, you might need to shorten the screws a touch as well, i can't tell by the pic how close they are to the strings. An alternative might be to put a nice hardwood spacer behind the bridge, and have your screws come from that after drilling the holes in the bridge upstand large enough for the springs to go through.
I would bite the bullet and move the bridge back to the guitar edge. Sure there might be two little holes but two pop rivets or a small decorative handle can sit over the bridge and tidy it up.
Edit- closer to the guitar edge, too far back will cause similar problems.
I don't know what products are available where you are Richard, but most epoxy timber fillers can be drilled right beside, or even 1/2 way across an existing hole once set, if you are careful, you could plug your old holes, move the plate back so it JUST covers the old holes and re - drill, a tiny patch of wood glued under the 2 front holes inside the box would almost certainly help to stop your plugs ever coming out. Of course you could do what i said without even plugging the holes, just use a thicker piece of wood inside the box to screw into, as long as you don;t slide the plate back too far and expose the old holes it should be ok
The thing is gorgeous though.