Play MUME, which stands for: Multi-Users in Middle-Earth
1. Rom/Duki or custom codebase. With a creation point system so you can pick stats and or skills.
Diku base, but *heavily* modified and also includes a custom language for non-c-extensions which is called mudlle.
2. 51 or less levels IMO if you can't get it done in 50 levels 50 million wont get it done either.
100 Levels, but levels after 25 are just 1/10th of a "real" level, so it comes down to like 37 real-levels or so (some 7 characters so far hit the 100, so do not count you'll do that soon

).
3. Remort system is fine but no reclass mud where you can get all fighter/mage/cleric/thief skills.
You'll not be able to play a "I have everything-character". You CAN prac whatever you wants, but the pracs you have influence the "pureness" of the your class. So, you can prac what you want but you should not do it. No Jack-of-all-trades here.
Stick mostly to a class, that's what you asked for, no?
4. Skill/class based.
Yes. Skill and class based, your skills determine your class (so you are not actually be forced into some pattern).
5. No twink mud IE RP just around PK (dont make me name names here) .
Roleplay is encouraged, but not enforced. If you do not want to RP you do not have to. MUME has an active base of PKers and is very PK-heavy.
6. Extended race selection maybe 20+ races to pick from.
Sorry, not that much races, but... you'll find it entertaining non-the-less. Oh, and trolls even have real-death if they walk in the sun at day, for those who like the extra-thrill.
7. Player crafting/mining/fishing/digging/trade type skills.
You can fish and in certain spots you can mine. The rest is sadly not developed.
8. Quest system of some sort
There are a lot of quests you can do, smaller and also bigger ones (as the one that lets you face the Balrog in Moria, known from books and movies).
9. Decent world size 10k + rooms stock or origonial I dont care.
10k rooms? More than the double of that are open in MUME! All oroginal and customly created, btw.
10. Player base can be small just nice and like to have fun.
Not as big as it was (you know, when the movies came out), but still active and you surely can meet a lot of people to have fun.
In general, MUME usually has some 30 to 60 players, nearly never below 20, in top times nearing 100. With players, I mean "players" which excludes wizards & builders.
11. Fantasy/midevil/AD&D type mud is best
"Tolkien" and "Lord of the Rings" rings a bell? Yep, exactly The Source that "inspired" (a)D&D and basically everything else.
Apart from that, MUME also offers a bunch of things you did not mention here. You seem like someone who does not want a sissy-game and you won't get it. There's just one disadvantage(?) that I'd like to point out as well: The learning curve is quite steep. But if you manage to find your way around, you'll have a lot of fun on that game! It surely is a very interesting experience, the game is around since '93 and currently it seems as if MUME won't face the fate of being shut down in the years that are to come.
mume.org
as soon as you have a character, you can visit the forum at mume.org/forum and ask all the questions you want to ask.