The orthodox way of using VC filters with a cold light head is to use filters that go under the lens. I believe Ilford still makes a set with filter holder.
The unorthodox way, which I use on my D-II, is to use 6" filters right on top of the negative carrier, held down by the head.
Do you have the Aristo Hi-D head? That's what I have, and it is indeed bright. I highly recommend using a compensating timer like the Metrolux, which can give accurate exposure times to 1/10 sec. Lacking that, you could put an ND gel (an ordinary lighting gel will do) between the bulb and the diffuser, and just remove it when you print big or otherwise need more light, but if you're printing on VC paper, see what kinds of times you get with a filter in place first.