Kerry,
I think Doug Mayer has that one (and many others) for the scale racing class, if that is what you are looking for. You can find his contact info on the NCLRA website. First, look up a 2020 issue of the Torque Roll newsletter and then go to the back to look at the supplier list.
If you are looking for a full-bodied, scaley deal, I would look for a copy of a Berkeley plan. I think they did one of the 'shoe. I know they did the Cosmic Wind in 1/8th scale. (Yup. Just verified, the AMA has the Boickly plan for $8. These were drawn by Paul Plecan had has a lot of great details.)
Of course, there is always the SIG kit plan. It is probably pretty close to scale. These are supposed to be within 5% I believe in order to meet the event rules.
If you are looking for a set of plans for the full-sized Shoestring, that's a whole different deal. But considering the number built, I'm sure they are out there too....
The Divot