You might change your mind after you put the PP2000 into the game. Anyhow, I do not know what Bruce did with his Titans tweeter; I do not even remember it they are in time-aligned position. The EdgarHorn Titans uses Fane ST-5022 bullet tweeter. I had them and I did not particularly care as about them, I think there are many better horn tweeters. Still, I once I heard Titans and they all together were very fine, with no problems of any kind in tweeter department. (I only once heard older Titans where they were OK, other times they were not good).
I would encourage you do not consider changing tweeters at this point. The PP2000 will have unstable in HF for a first 2 weeks, plus you have many new tubes. Try the “sit down test” from 1M – this will give you an idea if you tweeter is good match for you MF. Also, use only, let say, left channel and then use the amp from right channel to drive the tweeter with own dedicated amp. You might use the same passive filer as you have now but you will be able to change tweeter loading by the amp’s taps. This would allow to wary the tweeter’s sound to a large degree.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche