No, you can use pools just as easily.
That's excluding all user generated data? That's rather large for just OS and program data, what does this VM hold?
In my opinion, if you truly need VM primary drives larger than 265GB, then I would add the 1TB (1gb typo?) as an additional pool, dedicated to just the VM(s) primary vdisk(s). (domains share) Then you can use your current cache drive as storage for appdata and system shares, and as a temporary home for work in progress. Use the storage array for finished work, archives, and reference materials.
You could set up a share for WIP, and set it to cache only, then when the project is done move it to a cache yes share to transfer to the array when mover runs overnight.