Compressing LPCM audio while keeping original menus?

[ijuf]

i have an ISO which i'm trying to back up to a DVD with the original menus and everything, about 8GB in size(6.5GB video + 1.5GB LPCM audio).

i tried using DVDshrink w/deep analysis, and the only compression option was 50%, so i did it...which didn't turn out really good.

since i'm more over VIDEO than AUDIO, i wouldn't mind making audio down to like 200mb.
i know there's lots of ways to convert the LPCM audio to mp2 or ac3, but after studying the forums for 7 hours, i didn't really find the answer i'm looking for. since i want to keep the original menus and stuff.
i don't mind if it takes lot of steps in the process like using (IFOedit, etc.).
i'm sure i have to use something like this if i change the DVD structure(changing audio).

anyone have a good suggestion for this? it would save me a lot of time if i can get an answer. thanx in advance.

[ijuf]

By the way, i'm sorry if i post it in the wrong place or if there's any problems.
i'm not a smart guy so i'm sure lot of people would have found an answer to this after studying for over 7 hours.
in my case, i would not find one even after 50. maybe after 200 hours?
but don't have that much time for it.
Please help me out experts!