How much you know wasn't very clear from the start. UO since beginning had a bunch of updates called expansions and some of those expansions changed map count and map dimensions. Older clients usually means everything before version 7 :) in some cases anything before 7.0.24.x which was one of...
ced+ requires proper setup for flags when dealing with uop. So you probably failed to setup the correct value of the flag.
here is archived version of the setup wiki for ced+: Главная страница - CentrEd+ - Quintessence
so for map0 I'd use prefix value of 0 and Format flag 0x1C
There is multiple ways but first you'd have to state which UOP files are you trying to unpack? Is it classic client or enchanced one? Latest version or older one?
What kind of customizations? In general muls are a bit easier to deal with as you don't have to pack them into uop. so anything between 7.0.8 and 7.0.24.1 is good enough. I don't think there is a best client version as it all depends on what you want to do.
So after version 7.0.8 or something...
This may not be possible in regular client. Besides hardcoded weather effects, regular statics and effects have limitations for bigger image sizes :) So your best bet is to code some sort of a shader in CUO or similar custom client.
land tiles
textures
and tiledata
I used just 0x0003 land tile and texture as a source but it looks like everything is as it should be.
After saving files and replacing them in uo folder and in my centred server folder all looks ok. In this case ced# was used.
What are you replacing with what exactly? Is there any entry in TexErr.def for indexes that you are using? How tiledata texture mapping looks like for land tile?
What do you mean by worse? What's not working? No you shouldn't copy it to uo folder. UOFiddler is a separate application you just keep it somewhere on your hard drive and point it to your files which you want to view/update.
Get yourself latest UOFiddler, read readme to know which runtime you need for .net 8.0 then on the right you have releases polserver/UOFiddler
After you download the release zip right click and choose properties then Unblock. After that unpack the zip to some directory run it and set your uo...
I believe it was mirror of Grimoric's patched clients. Another instance of this is still available here: Папка из Облака Mail.ru Ultima Online Clients
Or you can use rtp/pat patch files on uogold installation and generate your own using patch server scripts and patches from here Index of /patches