Hi Bob ....You could try the Northern Aeroplane Workshops ( or Shuttleworth ) ....About 25 /30 years ago at one of the last held Sopwith Symposiums , there was an oldish chap there who had what was supposed to be , a complete set of the SL fittings / clips Drgs..(believe they originated from "Up North " somewhere ).
I didn't see them myself , but they might have been donated to the NAW or Shuttleworth , as I thought that this was the plan at the time ....Unless of course , " someone " got in first with offer of a big wad of cash ?
You'll be very lucky to ever find ALL the drawings of any WWI aircraft ,..But if you wait till then to start building , you'll be too old to ever build it !

There's always going to be some back engineering required somewhere along the line .
What's the state of progress on your proposed Snipe project ?..What motor will you use ?
Regards John