What English language author uses the longest sentences?

I’m trying to find something to compare writing to.

I belong to a writing group; sometimes submissions are intentionally florid. I don’t think these authors realize how their work compares to real, published, famous prose. So I want to find an English language author with long sentences. Preferably, it will be fiction. Then I can say, your sentences are as long as so-and-so’s__and they need to be as good.__

As a jumping off point, I can take David Hume’s Dialogues Concerning Natural religion and run them through an online readability machine and find that his average sentence length is about 28 words.

But certainly, there’s got to be a modern writer who can beat this. I’m not looking for the longest sentence, but a relentlessly abstruse writing style.

Whom would you nominate?