Well, all going back together now.
Everything was cleaned, the synchro bits even got a shine before refit, I've never seen the inside of a box looking so nice.
The forks went in easily as did the slider mech that operates them.
The 5th gear needle roller inner sleeve took a boil and good thump to put it back but it's there now, though it's a little more snug than it was. The thrust washer had perhaps 0.25mm play, now it's almost none but being on the outside side of the bearings it shouldn't matter.
5th gear selector went back no probs other than I needed to adjust it after a silly mistake. I didn't turn the nut at the same time as the allen bolt head so I ended up setting it too low. This revealed how easy it is to adjust, even with the box in the car. I reset it for now by engaging 5th using the selector mech and setting the fork height to make sure it was safely selected, then de-select and check it's well clear. I'll go over it again in car using the gear stick before adding the oil.
I'll also pull the torx screws back out as they've a blue coating that I suspect is threadlock, I'll clean them and apply some new stuff.
Tomorrow I'll reassemble the case and check the shafts end float. As they're supposed to be positive I'll use a slightly alternative method, I'll add a few thin shims (actually measured pieces of tin can) into the case gap and re-mate them then measure the float. I hope the output shaft is correct, there's a shim at the clutch end but it's in the blind bearing so staying put if at all possible. There's another at the other end but that's not easy to swap, it means taking the shaft and thus selectors back out.
If all goes well then it's just a smear of sealant, pop the new seals in and refit the flanges, refit to the car and check then a glug of oil.
Where's best for the oil, a stealership? Halfords don't stock it, their nearest of 80/90.