Well it might be an Al Masters, there are plans for a 56', 71' and 81' version of the Do from Al Mastrers plans. I am not certain if the plans are exactly the same in all sizes, meaning they were just rescaled with a computer program. I think the most notable feature you might be able to see if it is indeed the 71' version would be the long pieces of light ply that run from the front firewall to F15 which is the last fusage form that the wing attaches to.

You can see these pieces of light ply in the photos I have posted, I do not think that the Don Smith plans have this piece and I know the other un-named plans I have seen do not have these pieces. The Don Smith plans build a 95' wing span version so unless someone rescaled those plans down then I doubt you have a Don Smith plane.

Hope that might help you, when you get home shot a couple photos and post them, I would love to see it.