I’ve also been pondering what OSR system to use. Dunes was written with Labyrinth Lord in mind, but I’m not a fan of some of its details (Descending AC, Race-as-Class). I’ve been looking at a bunch of different systems (Black Hack, DCC, Microlite) to find the one I like best.
I’ve settled on Basic Fantasy. It’s an open source B\X clone, with more modern features like Ascending AC. It can be downloaded for free and has an active community.
To prepare for the campaign, I’ve gone through all of the encounters for the Dunes, and created a document in Basic Fantasy style with all of the conversions of every opponent from LL to Basic Fantasy. If you have Slumbering Ursine Dunes, (and you should, it’s great!) you might find this useful.
SPOILER ALERT: This 9 page document is just a list of stats, but it still might contain spoilers if you were planning on playing through this campaign.
The biggest changes are to the Armor Class and the XP values. I’ve tried to use Basic Fantasy rules for assign XP values to each creature. LL assigns XP based on monsters and treasure, while Basic Fantasy only includes monsters, so the numbers will be very different.
I’ve changed a few page references from the LL book to the appropriate page in the Basic Fantasy rules.