I don't know if its the Mk1 pickups or the Mk1 preamp, but almost every bass I have played with the Mk1 system in it has a harsh, artificially bright treble to them. Like the pickups aren't that bright so they add a tone of high end in the preamp or something. It's turned me off from buying some basses I would probably look at more closely with a different set of electronics.
EMGs are nice, but its a matter of are they your taste or not. EMGs sound amazing in some basses, while sterile and lifeless in others. I have EMGs in my Spector and I love them, but I have played other basses with EMGs and I didn't like them at all. As a rule, EMGs offer a very modern, edgy tone. Works great for slap, or modern, aggressive styles of rock or fusion. If thats your thing, you might like them.
But, I would strongly consider changing the preamp first, it might make all the difference. The Aguilar OBP-3, Audere 3ZB, or Bartolini NTMB are all very nice preamps with tons of flexibility. In fact, not that you need more options, but a very popular thing to do with the 55-01's on TB is to change the pre to one of the models I mentioned earlier and change the pickups to Nordstrand Fat Stacks. The Nordies aren't direct drop-ins, but I think they will go in with a minimum amount of modification to your Lakland. I think that is what I would do if I were in your shoes.