Help with reccomended soil mix.

So I'm getting exited. I found a guy that has 50+ vines or so that is weeding down his collection and is selling me some good sized crowns, he says they're about 4-5 times as large as the crowns Great Lakes Hops sells.

Here's what I'm getting.
Cascade (full crown)
Chinook (full crown)
Mt. Hood (full crown)
Tettnanger (full crown)
Sterling (full crown)
Hallertau (rhizome)
Saaz (rhizome)

I'm going to plant them on a southward facing hillside I have strung to eye bolts on trees. My soil isn't very good (clay) so I need to amend the soil at least close to the crown to get them off to a good start.

There is a local guy that I buy trailer loads of compost from that might help. Its horse manure & I think pine bedding composted together. Would this be decent for part of the mix? I was also thinking maybe some "black kow" manure, peat moss, 10/10/10 fertilizer and maybe some potting soil. Also how big of an area should I amend, I was thinking of doing a hole maybe 18" across and 18" deep.

With heavy clay, the bigger the better. The problem is that when you get a lot of rain, it tends to fill up the area you amended and just sits there until it has a chance to dissipate. No real proper solution but you could try to build the area up until you've created somewhat of a raised bed. Again, with clay, there's no easy fix. Any type of composted material will be a plus over the native soil so get as much as you can and have at it!

My raised bed worked well, filled it with 100% manure, 1st year hops grew 12' tall. Can't wait to see what they do 2nd year.

Well I ended up stealing some soil from my vegi garden, its been heavily amended with the horse manure compost. I mixed that with some peat moss and a bit of fertilizer. I dug the holes about 24" across and 12-16" deep. I will mound it up a bit as well. The hole was big enough to take 6 loads carried up in a 5 gallon bucket. Hope they grow well.

Sounds good. Since clay holds water, i'd tend not to go too heavy on the peat moss or use much perlite/vermiculite. My ratio for sandy soil is 1/3 organic compost, 1/3 perlite/vermic and 1/3 peat moss.