Nice guitar. I still love those old style wooden pickguards!!!
I wouldn't swap out anything until you played it. Schaller pickups are like any others... they have a sound that may or may not be what you prefer. If you go back and read comments you'll hear that they are hard, soft, bright, full, like an SD59, Alnico Pro II, a Dimarzio PAF or a Gibson PAF. That pretty much covers the range from left to right.
They are a potted, Alnico 5 based pickup, with 4 wire connections for coil splitting if you want to go that route. Schaller quit selling pickups which is what prompted Heritage to switch to Duncan (59s and Seth Lovers). They have 3 mounting holes on the baseplate, so you can adjust the tilt if you need it.
I've got Schallers in my H-157, Sheptone Tributes in my H-535, Seth Lovers in my Millennium, and Alnico Pro IIs in my H-140. I can make more of a change in the sound by changing my amp than I can between any of the guitars. Playing clean through the Princeton sounds nothing like the Patriot or the DSL401. In the end, what's most important to me how the guitar feels in my hands. Then I can tweak the tone to what I want.