Any suggestions for creating or finding presets for a Vintage Ludwig drumkit with Microtonic? I realize that this drum beast is not specifically designed for "real" sounds, i.e., no samples, etc., but can I get close to a simple acoustic 5-piece kit with Zildjian cymbals and hats?

I would respectfully say no. But you should checkout the vintage tonic presets to see if something there might suffice. "Close" is subjective....

Something I do when I'm working in Microtonic and want to use its sequencer to drive something else is use its midi output. Works great to drive something like AAS Chromophone or XLN XO. It could also be used to drive a more conventional drum vst but I find mapping between the two apps is generally more complicated. I use Addictive Drums for "acoustic" drums and there is a free , limited version of that that might be worth a try. Also freebie versions of vsts like SSD, BFD, Jamstix, etc

All of the Vintage Tonic presets sound surprisingly close to their "realworld" counterparts but are IMO quite electronic sounding by design. Something like the Korg KR55 presets might be closest to an acoustic drum sound. Making it sound like a vintage Ludwig kit specifically though would be quite challenging.

I realize this ask is a long shot, but hoping I could finally dump my drum sample library and their respective libraries in favor of Microtonic.

Only you can answer how "close" is "close" enough. IMO.

Just looking for a dry natural sound . . . doesn't have to nail it exactly . . . . just the vibe.

Natural won't happen IMO. A bit like expecting a wrench to work as a hammer (I'd start with the vintage tonic presets and see if anything there sounds remotely close to what you're looking for.) There's been some requests to incorporate the Genopatch technology from Synplant 2 into Microtonic which would certainly get you closer. But it will still not get a natural drum sound. It's (deliberately) synthetic.
I'd love for you to prove me wrong though. Good luck.