'a proper target' is correct and usable in written English.
You can use it when you want to emphasize that something is an appropriate or suitable goal. For example, "Setting a proper target for our sales team is vital to our success."
Then again, I'm not sure what a proper target would be.
What do you do when you start a race without a proper target to get your teeth into?
Lee said the Native Americans' "personal stake" in the case makes them a proper target for a lawsuit.
Waldron argues that hate speech could, in theory, be very consequential, and therefore a proper target for regulation.
The Defense Department decided to make the T.M.T.I. a permanent program, with an annual budget of more than two hundred and fifty million dollars, and the Pentagon issued a formal order that emerging infectious diseases are a proper target for military research.
The F.D.A. doesn't have to listen to its advisory panels and has yet to decide on a proper target range for levels of red blood cells — but when it does, analysts say, it will almost certainly be lower than what DaVita was aiming for before the safety concerns intensified.
It lacks a proper targeting on its own and if not properly administered, will not give a good end result [83].
Formation of a stable complex between P4-ATPases and Cdc50 family members seems to be indispensable for a proper targeting and functioning of P4-ATPases.
The first task of the TOA-association approach consists in substitution of the distributed target with a proper simple target.
In taking a stand on what the proper target of a first-order legal theory is, one incurs a number of other methodological commitments.
One question that immediately arises is which concept of law, exactly, constitutes the proper target of a theory of law.
