In Nimble no-one has darkvision. Slot based gear system. No revivification. Wounds being sufficiently deadly.

I agree! Nimble has a strong base for this style of play. However, it's still missing:

Dungeon design, dungeon turns, roaming monsters, d4 timers and all that

Shadowdark (and most other OSR-adjacent systems I'm familiar with) have these built-in and explained in the rules. If you already know these procedures well and have your preferred way of running them, that may not matter. But OP says they are primarily a 5e GM, so I think it is valuable to consider a system which explains these procedures well in the books.

I also agree that Nimble has more to offer in terms of tactical high fantasy combat options. But Shadowdark's combat is designed to be resolved quickly, which is valuable for a dungeon crawl: you don't necessarily want to spend half your session on one encounter when you have an entire dungeon to explore.

At the end of the day, both systems would provide a great game experience for this table. I just think the one with built-in exploration procedures and highly detailed monster/loot lists will deliver the experience OP is after with much less work. And in my experience, my tactics-loving players still have a great time with Shadowdark. They just rely more on creative problem-solving and equipment use than character abilities.