[Jim Koehler]

What works nicely are the Dale bolt on resistors. Once these candohm assy's start going, the smart money is to replace the whole unit. With the proper Dale resistors replacing each section in a Candohm, you have your resistor taps right there. The biggest worry is how many holes you're going to drill on the rear apron (or wherever the old unit was mounted). 
Another point is some candohms run HOT! This would be the perfect opportunity to bring up the wattage on that hot running section....easily done with a Dale resistor. 
They're low in profile so they fit in about the same footprint of the Candohm also.