You should be able to, though you'd end up with the equivalent of late production DQ-10s rather than your early set. They'd be the most sonically improved, of course. As for the schematic, you'd want to adopt the one with the last set of revisions that can be found here along with a parts layout to help sort out what goes where:?/g/DahlquistSpeakers/wiki/23560?You'll see that the crossover layout is a bit different and, depending on how up to date the XO was kept with the revisions, how things are wired in the center and top right of the boards may differ, but you can work with what's already there.
The metal dome driver does look to be a LPG, though I can't say which model without seeing the side of the motor and even then it'd be a guess. My guess would be that it's the PMK51, which was quite popular for awhile:
If you go for MB/Peerless replacements, whatever drivers you get will already be decades old and have aged suspensions. So, there's nothing gained by replacing both. Just one will suffice and make it easier to find.
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Re: Advent woofers. Per Jon Bader, Dahlquist's service manager of 15 years, the Dahlquist woofer's biggest difference from the Advent type was that it used a different technique of how the surround was glued along with a different cone treatment that improved its top end performance (outside of the passband for how it's used in Dahlquist models anyways). In our facebook group, a driver designer for Gefco, the manufacturer of the drivers for both Advent and Dahlquist, chimed in recently saying that the voice coil former in the Dahlquist also differed in that it was phosphor bronze, a material used in the 1970s to improve power handling (handled higher temperatures better). These differences are fairly minor at this point given how much the drivers will have aged (again, suspension compliance changes and alters the T/S parameters significantly) and so they can be used interchangeably without notable difference. You do have to refoam either of them correctly or the voice coil won't be centered in the flux in the gap impacting linearity and excursion limits.
