Different system, similar situation. The 80mm on my 6x6 Bronica has a close focus of 80cm. I considered getting an extension tube to get closer for head/shoulders shots, but soon realized that the perspective would become very awkward. The 150mm by itself wasn't a solution either, as without extensions tube it focuses no closer than 150cm, giving the same magnification as the 80, albeit with a flatter perspective. In the end, the solution for me was a 2x tele-converter. With the 80mm mounted, the FOV is comparable to 160mm, but the close focus distance remains the same 80cm as that of the lens, allowing a 2x tighter crop. Downside may be that the effective aperture becomes 5.6 @ 160mm, but you'd have an aperture penalty for an extension tube as well. What's nifty again, is that you can focus from 80cm to infinity and back without removing tubes or diopters..
Not sure what the situation for Hasselblad is, and whether a matching 2x is available for your 80mm. (The PS2x Bronica converter was specifically designed for the PS80 and up, so the quality impact is minimal).