Excellent!
Yes, I'm sure you will be able to get close using your beauty dish and softbox. In fact, IMHO, if you have some extra softboxes, you might want to try putting them on either side of the camera, just not for subjects (like faces) that need some shadowing on their sides to give a sensation of depth.
In addition to the advantages of a long lens that you mentioned, there is another major advantage: At a fixed f-number and fixed magnification, as one increases the focal length, the depth of field increases. Since his signature look always has a large depth of field to preserve the appearance of a traditional illustration, the long lens definitely helps in this.
BTW, one normally thinks of long lenses as throwing the background wildly out of focus (ie, much larger blur circles than shorter FL lenses). This is not a contradiction with the property I mentioned in the previous paragraph. The depth of field is measured along the optical axis whereas the diameter of blur circles are measured perpendicular to the optical axis, so they are distinct properties. Basically, with a longer lens (at constant magnification and f#) the blur circle stays small for longer as one goes to either side of the plane of best focus, but then once out of the region of best focus, the blur circles expand more quickly than those of a short FL lens (at the same mag and f#).
Let's stay in touch.
Best regards,
Tom M