[TowerTalk] Cushcraft XM240 stack distances

[AB2E Darrell]

Hello all,
I have a 120ft Rohn 55G tower in the works.
I'm wondering if it's practical to stack a pair of XM-240 Cushcraft antennas?
If anyone has this setup, what are your stacking distances?
I'm thinking top one at 120ft rotatable, and 2nd one at 60ft fixed on EU, but might be able to get TIC Ring or similar.

I know K3LR has a stack of XM240s (Moxon mod) at 120 and 170ft, but I can't go that high.

Your thoughts and comments appreciated,
73 Darrell AB2E