I went searching for this animal last year, and came up empty. I was hoping to find a 'screw-down-cap' master cylinder to get away from the bale.
I just got an email with this product from SSB.
Here it is, for those interested
SS Brakes Billet Master Cylinder (http://www.ssbrakes.com/newsletter/200502.page5)

JR

Seems to me something similiar to this has been being advertised for the past couple of months in the Goodguys Gazette. I love the idea, it'll work great in an engine compartment full of billet.

Autozone and Kragen out here sell the bolt down type Master cylinders as standard now- not sure about where you are? They aren't billet though.

OPG has one in their catalog. A little pricey.