I don't own a 40 but the inner windshield moldings appears to be the same from what I see in the best convertible picture I found:
http://imagehost.vendio.com/preview/da/danschmitt/405068-28.jpg
Is it just the height or width? Thickness? Mounting holes? Mirror cutout? Curvature?
All of the above?
Trust me, they are quite different. The cowls do not resemble one another (closed vs. open types) so it follows the moldings would be different. Even the 40 open car moldings are different than the 39 open car moldings.
You could use
pieces of closed car moldings to graft in to the open car set to facilitate repairs.
And, as a retired tool maker I can tell you first hand that you could make a set out of closed car moldings. It all comes down to talents and time.