NO, please don't waste all that time...
Some chat first...
If you when making your level take a texture from here a texture from there, you will soon end up with a 2mb unr for your level, but 20mb of utx's to make sure go with your level.
Or you go thru all the texture packs you have and decide, I will use that one and that one, and make sure you stick to it, ending up with just those two to zip and put with your level.
What I do is this, I tend to use standard UT texture packs where necesssary, I guess as little as possible becauee UT ones are a bit old now.
Then I just create and add to my new custom pack as necessary.
Some rules that I adhere to... Never ever change or update either a UT standard or anyone elses texture packs, this will cause ppl lots of problems with texture file version differences.
After I have sent out a custom texture pack to the big world out there, I never change it... I guess because a 5mb to re-ftp when only one texture has changed or added, rather than making a small new one or even just stuff it in the levels internal texture pack "Mylevel".
Ok what you can do with your level which EVEN if you retextured the whole thing by hand there is still some hidden surfaces that you can't see hance can't get at BUT they DO have references to these texture packs you DON'T want to package with your level.
You can edither export the whole level, exit the editor, reload the editor and import your exported level, you will see that all your geometry has been striped of all texture references. Just a case of retexturing it with the NEW textures you wanted...
Or... A excellent tip Andirez passed on to me is this... You can CULL (Kill/Remove) all of one textures references within your level by HIGHLIGHTING the texture (just one surface will do) and type in "texture cull" at the command line, this will remove ALL of that texture from your level, I assume replacing it with the default one.
Bastard'O