Hi there,
Started planning a tour a few days ago but was knocked off my bike and now have to postpone. In addition, I will have to reconsider my rig. I was planning on taking my Cadex CFM3 with a light load and stiff forks. It is an old but sturdy lugged CF frame. It had a nasty knock in the accident, and I am not sure that I feel comfortable using vintage CF after that. Wheels are also badly buckled and probably shouldn't be used for a tour.
My new option-
Buy a new touring frame (surly or similar). Might as well get one with disc mounts...
The best candidate for a wheelset I have on hand is Sun Ringle Charger off my MTB. Very sturdy and quite light, but obviously not designed for touring. What do you think, could I use that wheelset? My main concern is that I wont be wanting to use MTB tyres, but a skinnier, slicker option (ideally 26x 1.4-2.5ish). I am not sure how to evaluate how skinny a tyre the rim could safely support.
Thoughts?

I would get a new set built up for the touring bike. Lower spoke count wheels don't make a ton of sense for touring neither does old carbon or more racey bikes. People do tour on all sorts of stuff but getting a nice stable sturdy touring rig is probably the best way to go.

Most touring bikes are not built around 26 inch wheels. In any case, it is a relatively expensive proposition to build up a touring bike (or any bike) from a frame. If you're looking to save money, buy a quality used touring bike.

Crashed, lugged/bonded CF frames are certainly not ideal candidates for loaded touring. Crashes, heavy loads and frame deflection cause joint failure. Early Cadex models were known to occasionally come apart at BB/seatstay/dropout joints. I once owned a Giant Cadex 980c road bike which was subjected only to the intended use, treated gingerly and it held together until I sold it many years later.

Surly LHT/DT framesets are hard to beat if they don't cost too much in Oz (in USA MSRP is $479+tax). I recommend the 26" wheeled version as it has some longevity/fitment/handling/tire availability advantages over 700 version. I have owned and used both versions.

Sun Ringle Charger (24/28H) wheelset is like the Cadex, lightweight and flashy but not ideal for loaded touring. They might hold up if they're in good shape (see a wheelsmith) and you are not very heavy and you also carry a light load. A better idea is to buy or build 36h wheels with Shimano hubs and robust rim. Cutting corners on wheels is a bad idea for loaded touring.

Best size tires for touring is 26x1.4"-2.0" (1.4-1.75 for pavement, larger for off-road). I include 1.4 because Ritchey makes the Tom Slick in 1.4" which is the lightweight end of the touring spectrum IMO. Anything smaller will be highly subject to punctures/damage and not be very long-lived. Anything larger than 1.75" is noticeably heavy rotating weight, so use these only if anticipating significant amount of off-road riding. LHT/DTs accommodate up to 26x2.1", w/wo fenders.

ETRTO chart near bottom of linked page provides rim/tire compatibility data:

https://www.schwalbetires.com/tech_info/tire_dimensions

Yeah, came to those conclusions anyway. Settled on this frameset:
Wayward Bicycle Company
reviewed as a decent, Australian alternative to an LHT, good chance to support a local
Picked up a heavily discounted 28/32 spoke 700c wheelset by wheelcraft
Click Bike bicycle clearance boutique (Salsa Cycles & All-City Cycles)
I only planning on carrying about 10-15kg on the rear and max 5kg in a handlebar bag on the front. I like to travel light and will never be far from a town on my planned route.
Most other components from the Cadex are still in good nick and will work well with the set up.
Thanks for the replies!