So We The BOS At The End Of BS Had Vertiberds,Hellfire PA And A Whole Bunch Of Enclave Tech.(Assuming You Were Good) So Where Would They Be Strentgh-Wise As Of 2290?

Assuming that they went onto vault 87 through searchlight and kept recruiting locals and running the purifier, I'd say they're sitting pretty good.

Barring some unforeseen disaster, I think it's safe to say that the Capital Wasteland BoS will be a major power by 2290. The major settlements of the Capital Wasteland will likely be united under their rule by then, and constant recruitment should have swelled their numbers greatly. Equally, given their access to large supplies of Enclave tech and an intact Enclave base (Adams AFB) I wouldn't be surprised if they have begun to manufacture advanced technology on their own; they've certainly got access to the necessary factories to do it.

The Capital Wasteland is poised long-term to become one of the major powers in post-War America, perhaps even rivaling the NCR in size and strength with time. As far as its immediate future goes, though, the constant supply of clean water, large stocks of advanced weaponry and armor,and well-trained and numerous defensive force should keep it strong and secure.