RE: Old Shrike back in the air today (tail wags)
Your plane is probably a little tail heavy.
Advance your CG a little bit, like 1/4 or 1/2 inch. The plane will come a little hotter on landing, but will be more stable at high speed.
I Have the same trouble with my little Wonder .10 when I put a OS.32 on it. Advancing the CG by 3/8, solve the stability problem.
Hope this help.