Can I adapt some Liu He Ba Fa?

No.

My teacher showed me things about water boxing that a video or book couldn't. That form is essentially a complete martial art that is extremely effective and misunderstood by most.

Be careful, some Chinese folks aren't too keen on white boys learning their secrets.

If you've been a good studier of the other arts you've mentioned then you might be ready for C. water boxing.

The leading authority on 6/8 boxing, now semi-retired, is Grandmaster Wai Lun Choi of the Chicago area. He used to teach 6/8, taiji, qigong, baguazhang, xingyi, and tibetan lama in his studio on Irving Park Road on Chicago's north side. IIRC since about 06 or 07 he has been semi-retired and only gives privates and does seminars. Check his website.

He was workjng out some instructional DVDs but I do not know where the project stands.

There are several reditions of the form out there, the best known one by Helen Liang.

However, these versions differ from Choi's "canonical" version.

It is possible that some of Choi's former students teach the form, but you would have to find them.

6/8 is not taught in public kwoon to any great extent. In China it was a "closed door" art.

I would take Fang's advice.

Just show that you are worthy to learn it. Many times you won't know they teach something and if you're not a good student in their eyes, you won't learn the good stuff. If you are - you will learn a lot!

Providing you are training under a Chinese Teacher.

Edit:

But seriously - don't adapt it - train in it. And that goes for anything.

I was a student of Master Choi in the late 80s. No one moves like he does.

If you can find one of his senior students, go for it.