If you don't own a Machinery's Handbook - you should.
Actually these days this type of information is usually readily available via the internet.
depth = p/2 http://tinyurl.com/yf7kg2a
The only R20 feature I see should be a trivially easy Presspull through the part!
center line track vertical
offset half width either side
Presspull (actually don't even need to trim for press pull