Rail sizes will not match and will not work together in a single fixture.
Problem is what you read - hinging is not at all 'nearly impossible'. There are several methods of hinging and they only take practice and patience. Try the rail head and base cutting, leaving the rail web as the flexing hinge technique. Just enough metal to hold and be reliable - just not enough material to allow bending flex. Has electrical continuity as a bonus.
-ed-
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-ed mccamey-
COSLAR RR -
http://www.coslar.us/NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.