I agree with Dave...the lock plate is best if it is flat. The only issue with that is that modern locks have a bevel. L & R's Ashmore lock has a very very narrow bevel, and some judicious filing could remove it completely. I think that is your best option....unless you can sweet talk Bob Roller into making one for you - then you'd have something special and correct.
When thinking about the panels around the plate, there are many variances. I would study J & S
Hawken examples for inspiration there. But panels from their long history of work would be fine as well.