There is a problem in this area as the Williams repair manual http://www.planetarypinball.com/reference/partsmanuals/WMS_Parts_Green_16-9932/index.html#/38/ clearly lists this as a slow blow, but there are many operator manuals that say it's a fast blow. I would say put in a fast blow and run display test, if it doesn't blow you are golden. If it blows during test, consider changing it to a slow blow. Eventually you are going to have to replace the original plasma display, likely with a newer low voltage display like a color DMD or LED display; after you do that, just pull 601 and 602 off the board and throw them away since the HV section of this board will no longer be needed.
If you do pull the fuses, you want to also tag the board to say why there are no fuses as a reminder to yourself, or for the next guy if you decide to sell the pin.