Sorry, dumb question.... what you want a vacuum tank for? Can't see why it wouldn't work though.
My Patrol, like most GUs, had 2 pizzy little black canisters in the back corner (passenger's side) of the engine bay. They were plumbed up via a clumsy system of steel and rubber hoses/pipes that seemed like they were put in there by a drunken Jap on steroids on a Friday afternoon.
When I decided to fit the electric vac pump (see the post I recently put up in the Mods section), I decided I could do without 90% of that pipe-work and the best place for the pump was deemed (by me) to be the spot where the 2 black canisters were mounted.
So the canisters came out and I added a vac gauge to keep an eye on my available vacuum. Each time I use the clutch or brake, the needle drops quite a lot, so I decided to add an extra tank. Haven't fired the old girl up since I did the mod, so I don't know how much of an effect it will have.
I have to run my young bloke up to Port Broughton for a Karate grading on Sunday, so will fire-up the big Chev donk for that trip.
If anybody does decide to ditch the 2 black canisters, just be aware that there is a non-return valve located inside the black, solid rubber hose that joins these 2 black canisters together. I made sure I incorporated that piece of pipe in my new plumbing arrangement.
I removed the steel pipes down low (near where the turbo would be on a normal 4.2Td or 3L TD). If you have a look at the pipe work there, you will see what I mean; bloody pipes and hoses going in all directions.