It is possible to compile the teth to exceed the limit of 200 level to something like 300?

Yes. But the ship is the easy part. You also need to change the client to increase the level limit. You then need to edit the player level table file adding the extra level up stats.

Hmm interesting I'll try to do that soon, once tried something like that but when I exceeded the 200 level I was disconnected

There's a few places in the client you need to update. You also need to edit the player level table file (PlyLevelTbl.bin) which I don't believe there's a public tool to do. I created my own and do plan to release my tools to the public at some point. Once you've got that done the ship code need's to be updated; tnlxp will require the additional required exp entries. Then search for character.level in the source code and ensure that tests for 199 are increased to the new cap.

I've not tested increasing the cap to 300 but tested increasing it to 220 which worked fine.

understand me now I know why it didn't work I modified just a source of teathella the strange thing is that when compiled wasn't reported no error but in theory as I said before not work xD
but that's okay I'm going to do my best and try to make this stuff soon I want to thank you for not only helping me in this matter but have also helped many other communities directly and indirectly, thanks tofuman long life to you and to eden ^_^