Just some random thoughts.
Stocking the Megadungeon. Man, popular post. I've decided to give the Basic/Expert stocking rolls a go initially. If it's not satisfactory (or maybe even if it is), I'll try the AD&D system for a section or two.
Converting 3.0 / 3.5 / Pathfinder / d20 vs. early games - Both have their own difficulties. If I grab an old AD&D module, I can glance at it and tell you how tough the monsters are, how rich that treasure is, how difficult that save is to make. Then I can let that inform my idea of what I'd like to do in my GURPS game in that circumstance. I'm fluent in the system. On the other hand, they often lack critical details, because for all the talk of "in old school games you can do anything" they didn't really give you rules for everything, and often skimped on details. So rivers show up without discussions of depth or current speed, doors are just doors, bars are just bars that bend normally. It's up to the GM, and if I have to make it up myself using a pre-written adventure isn't saving me a lot of time.
With 3.x and later games, you get a lot more real world detail on the surroundings. This helps because a 12" thick oak door is something that has stats in GURPS, so I can easily see what they were trying to tell me. The downside is that I'm not fluent in 3.x or later, so feats, stats, etc. mean nothing to me. I need to look them up in the SRD and then try to figure out if they are meaningful. It's easier to just look at pictures and read text and get an idea and then just make it up in GURPS from there.
Either way, converting leads to some time wastage as much as it saves time and allows me to re-visit things I'd like to try with a new group. But because of system fluency, and nostalgia, I'm more likely to use older materials. Not to mention I have so much of it just sitting here in my Box O' Adventure Modules.
Norkers and Map Annoyances - I started re-reading WG4 The Lost Temple of Tharizdun.
It's a good adventure, with lots of flavor to it. It even uses norkers, one of my favorite humanoids. I've used them before in GURPS, when my 1st edition GURPS buddies went through Grakhirt's Lair (hey, I just noticed John Nephew wrote that, cool). Annoyingly, it's got some map foibles. It has text referring to Maps #1 and #3, but there are no maps #1 and #3. There is an Ariel View map (clearly Map 1), but that's not the one. It's got this annoying inset display map, with highlights that don't match the larger scale map, details that are hard to line up, a different numbering scheme. Man, I never did puzzle that out when I was running AD&D in Elementary School, let me tell you. Maybe that's why I never ran it (not that I recall, anyway.) Other weirdness is in there - you can read about it here if you like.
The coolest thing about it is the battle roster for all the inhabitants of the lair, and details on reactions to followup raids. That and references to the boss monster dungeon raiding for fun and profit. ;)
I don't expect that the inhabitants would be as tough in GURPS 4e DF as they are in AD&D, just from relative damage-dealing ability. But at the same time, they are a bit more dangerous opponents . . . it only takes a good roll or two to drop a PC no matter how good.
Anyway, that's my random notes for now.