OK the bearings are 688rs not 608rs as I wrongly said earlier, so they're 16mm outside dia. 8mm inside diameter and a width of 5mm. I'm using two at the end of each chainstay where it meets the seatstay by the back wheel dropout. I've had to machine a little alloy collar / spacer (16mm o/d x about 12mm I/d x 5mm thick which will be bonded into each of these bearing housings to provide a stop for each of the bearings. As the bearings have an inside diameter of 8mm the original alloy bush fits perfectly. At present two nylon washers 22mm o/d, 8mm I/d and about .75mm thick flank the bearing housing. I might change this at a later date to allow sealing but that would involve making some stainless top hat shaped washers and shortening the original 8mm diameter bushes and I didn't want to do down that route in case I wanted to revert to stock setup.
At the top of the seatstay where it meets the shock link I'm using four 688rs's. Here two sit in tandem at each side of the chain stay top. I've turned a bit of alloy bar down so it fits snug between the inside faces of the link and a shoulder on each end for the bearings to sit against so they can't slide too far in. Imagine a cylinder with narrower bits on each end. Again I will initially use Nylon washers to prevent lateral movement to start with. I will post pics or diagrams at a later date but its late and some bits are at work.