I also built several Sky Glass kits in the 70's. That looks like a P 6 to me also. If the tail fin is slightlty tilted to one side it's definitely a 6. Lots of the P6 kits had to be cut apart down the top seam and re-glued to fix them. If my memory is correct, Bob Reuther was the originator of Sky Glass and sold them through his hobby shop, Hobby World.
Dave