Hello Jean Paul,
I have owned several Telrex antennas through my years as a DXer. In my opinion, you should optimize the 20M546 beam using available software such as Antenna Optimizer, AO, or Yagi Optimizer, YO, by Brian Beasley, K6STI.
Be careful how you estimate the affect of the elements passing through the boom...I have some thoughts on that if you're interested.
Telrex antennas are big, huge beasts. They are physically the best (not considering wind load) I've seen for the amateur market; however, the electrical designs do leave something to be desired when comparing their performance against modern-day yagis. The 'Balance Tee' feed system is certainly the best way to feed a monoband yagi; good even-order harmonic suppression.
Vy 73,
Ted Algren, KA6W