Bare Knuckle Mules are a good choice for the Marsden if you want Classic PAF-ish tones. A4 mags.
This is my Bernie when I had the Mules in both neck and bridge positions:
If you're thinking of splitting the coils with a push/pull the you want 4 Conducter and short leg pups (Although long leg may also fit)
You may get better split / tapped sounds with higher output pups so it's worth speaking to Tim at BK.
The Mann 2300 stoptail is a perfect mod for the Bernie. Looks good, works perfectly, improves tone, etc...
As Bodia said, the stud wells are a perfect fit and are as quick to swap as a set of new strings.