It's a Bendix master - known as a double hump. The part number of 2660809 would be correct for your 69, even though the listing above from the Ram Man has it as 71.
Again, what's wrong with the original in you picture? Often it's the surface of the master cylinder that is knicked or uneven, and they leak no matter how good the gasket is. I cleaned mine up with a file and no more leaks. Protect the reservoirs and fluid from filings of course...
Agree with all of the above providing your original gasket is toast, and/or the master cylinder to gasket surface can't be refurbished. We need info here!
Edit - seeing your new post just now - if it leaks, try making sure the master cylinder's edges that the gasket seals against are true.