I'm not sure what spring rates or lengths to use yet. As far as the spring lengths go, I figure I'll get the shocks all assembled then work out how long they need to be.
For length your choice with an Eibach spring is either 8" or 10". 10 for the back easy, 10 for the front if you can. Both may need the extra groove put onto the shock body to accomodate them. Would suggest 10" all round but the front ride height may be a problem so get the grooves put under the existing ones (down aways too). How long is your sleeve?
Based on what other people have used, and the fact that the BNR34 is heavier, I'm guessing 325 lb/inch front and 275 lb/inch rear?
And will these spring rates work OK with the Bilstein shocks or will I need to have them re-valved?
6kg/mm & 5kg/mm are reasonable numbers. Bilsteins will be fine in this range. You would be surprised how large a srping variation they can accomodate.
For the bump stops, where do I get them from so I can cut to suit the block height?
And is 30mm about the right measurement to avoid block height occurring?
Stock bump stops are good if you have them. You have to try before you can get them to length. This is a pain but has to be done.
And excuse my ignorance, but what fixes the sleeve to the shock? I see mention of having to have grooves machined in the shock body to accept a circlip but I can't picture how this works.
If you have a look at the other thread the photo in post 12 shows the circlip in the top groove. Tiny circlip is tiny but is trappped by the bottom of the sleeve.