Personally, I believe the Oregon zoo should play things carefully in regards to acquiring a new bull. They are one of the lucky few facilities that haven't had any issues with EEHV, and I would very much like to see it stay that way.
Personally, I think billy would be a good bull to send over, he is large and impressive, and has absolutely no offspring, making him extremely genetically valuable! That said, who knows if LA would be willing to send him out. In addition, he is also owned by Have Trunk Will Travel, which after the whole affair with Tusko, is not something I think the Oregon zoo would want to deal with again. Perhaps they could acquire semen from him for AI ?
I could potentially see them using semen from male from ABQ,however ABQ seems to want to keep a hold on their current animals.
Also as a side note, ft. worth's males are Colonel and Romeo right now.
Also edit to add: Tucker is actually owned by Houston now, they bought him and Tess a couple of years ago. I doubt they will ever transfer him though, as he will most likely come the new breeding bull once Thai passes away.
As for Billy/Budhi at Denver, breeding from them wouldn't be the worst, but it would make more sense to AI from Groucho instead. The first two are both grandoffspring from Motek and Warda, who are very well represented in Europe, and have many relations over different generations in North America as well. On the other hand Groucho only has 2 offspring and 1 grandoffspring.