I’m still waiting on my hardcopy of Torchbearer to arrive, but I already see it as my primary dungeon crawling game going forward. That said, I think that some old TSR modules should prove to be, at the very least, great ideas mines.
In your opinion, are there any old TSR modules in particular that stand out as good candidates for conversion to Torchbearer?
I’m actually converting a bunch of DCC RPG modules at the moment, which are definitely spiritual cousins to the old TSR ones. I think TSR modules will be fine, but one thing to be weary of is the size. Your group is only going to clear 3-4 rooms a session so some of the larger ones will take quite a while and may potentially even be an entire campaign unto themselves. I’ll get my notes on how to handle conversions together and post them soon.
I’d definitely be interested in seeing those notes. I’m also currently eyeing some of the old (notoriously hard) Arduin dungeons for conversion. 
I ran in C3 Lost Isle of Castanamir using TB.
It works, but it’s a bit overlong and the absence of an available town REALLY ratchets up the difficulty.
I’m curious to try Cult of the Reptile God sometime soon. It has closely linked town and dungeon portions, but town is sort of adventurey.
I’m looking forward to running Tomb of Horrors and/or White Plume Mountain in Torchbearer.
Yeah, adventures that have a lot of in-town intrigue are a little more challenging. I think those are best dealt with with the disaster table. Basically, the adventure doesn’t start until you roll a disaster event, and until it’s resolved, they can’t take advantage of the town. Brutal, but part of their reward can potentially be a discount on some of the amenities in town if they save/positively impact it.
As to general conversion notes:
[ul]
[li]for D20, every 5 points of DC = +1Ob (ie, DC 15 test equals Ob 3 test)
[/li][li]For old AD&D stuff that uses the d6 for a ton of stuff, take the chance and subtract it from 6 (ie, 1 in 6 to open a door mean 5 Ob, 3 in 6 means 3, etc).
[/li][li]Certain things, like navigating water features, are harder in Torchbearer than other games. Count factors in these cases.
[/li][li]Loot is an issue. These are by no means hard rules, but what I have been doing is this: 1000 cp = 1D of coins, 100 sp = 1D of coins, 10 GP = 2D of coins
[/li][li]Platinum doesn’t exist in the TB handbook, but you can either factor is like gold above so 10pp = 3D or double the amount listed in the adventure and count it as gold
[/li][li]
[/li][/ul]
Thanks, everybody, for the suggestions. And thanks, vanguard, for the conversion notes. My copy of Torchbearer arrive Thursday and it’s a beautiful thing. The workmanship is awesome. There’s something particularly satisfying about the texture of the cover. It reminds me of old school (circa 60s/70s) hardcover books. Yeah, I’m a little weird when it comes to book fetishism. 
You are not alone on the texture thing - I talked about it in my review!
Oh, good! It’s definitely got some appeal to it. Reminds of the books I checked out from the school library as a kid. 