Mike,
There is actually little difference between early boomers and later fast attacks in overall length, beam, and draft. For example, The SSBN 598 class measured 381 feet in length with a beam of 33 feet and a draft of 29 feet. The SSBN 608 is 410 feet in length with a beam of 33 feet and a draft of 27 feet, whereas the SSN 688 measures 361x33x31 and the SSN 21 measures 353x40x36. It is only with the USS Ohio class, Typhoon class, and Delta IV class the the size of the boomers take an appreciable jum in overall length, beam, and draft.
Also, don't forget the Oscar class SSGN. In other words, at 1/144, modern boats, whether SSBN, SSN, or SSGN (with few exceptions) could be quite monstrous!
Bill