I also made a Greenland paddle using the dimensions described in Chuck Holst's plans, and mine ended up being 75" (I'm about 5'1" tall). I have a fairly narrow, low volume kayak so it works pretty well. I have small hands also, so the width of the blade is only 3". This makes for quite a small surface area for the blade and I have found that I get better speed by using a sliding stroke while paddling. I plan to make another paddle about 84" long as a "cruising paddle" and use my shorter one as a backup-almost-storm-paddle.
I love paddling with the Greenland paddle now. I find that my paddling is much more relaxed, and using the sliding stroke feels even more natural than keeping my hands in a fixed position on the paddle. I definitely notice a difference in the strain on my wrists and shoulders. I have to make myself use the Euro paddle now and then just so I don't forget how!