OK, I'll tell you what I did when I was in the exact same situation in the fall of 2008 with the throat on my .22-250 LRPV shot out and a gunsmith friend willing to load me a reamer.
I got Gordy Gritters and Richard Franklin's videos. Gordy's is just chambering but it is very good. Richard's covers every thing from chambering to action truing. I watched both videos several times. The first time I just watched them. The second time I put MS Word on the second monitor and paused the video to take notes. I've watched them both about 4 times now.
I also went on several forums, the gunsmithing portion of Bench Rest Central was a very good source of information. I did searches on chambering and read the posts. I copy/pasted the best parts of threads into an MS-Word document. I followed links to WEB sites, copy/pasted good stuff from there into my "chambering book". I ended up with 200+ pages of book on chambering. I put it in the throne room and spent hours reading it.
I wrote out a procedure that would work for me in my lathe. Then I started making tooling.
My barrel vise:
Adaptor to use a dial indicator on the tail stock:
Spider chuck for the front of the headstock (I used my 4J chuck backplate):
A cross slide threading stop:
Couple of receiver truing sleeves:
These are used with a set of bushings I machined in .0005" size increments from .698" to .705". I used a chucking reamer to ream the ID of the bushings to .500". For a mandrel I bought a 14" piece of 60R precision ground shafting from MSC.
To be continued.