Since the Dean Custom 350 comes with humbuckers stock, it almost certainly has 500K pots (which is to say a pot with 500K ohms resistance between the "0" and "10" position) since that the most common value of volume pot for humbuckers. Since you are putting humbuckers in there again, there's no real need to change the pots and get a different resistance. A lower resistance such as 250K would have less treble, and a 1M pot would give you even more treble than the 500K, but 500K is apparently the sweet spot to most player's ears.
Also, since the guitar has coil splitting built in on the tone knob, if you were to replace the tone pot, you'd need to get one that's also a push/pull knob for the splitting feature, since they're all one unit.