Lining up a two piece round pattern

[Gary Koval]

I am trying to make a simulated wooden barrel top, made from two pieces, (of multiple boards), to equal 22" in circumfrence. This will be used at my sons wedding for guests to sign. It consists of two pieces an approx. 13" side (and I'll use three pieces 5.5", 4.5", and a 3" pieces) and an approx. 9" side (with a 5" and 4") board. The boards will be glued up prior to carving and I will use a sled. I have watched Micheal Tyler's, Tips and Tricks, July 09', but because this project is round, and does not have equal sides as in the video, plus the 9" side is the down (smaller) side, of the circle, I'm having a problem lining them up. Any help is appreciated...
Thanks,
Gary