Are Record and Stanley brand smoothing plane blades interchangeable?
They should be interchangeable.



You can buy a VERITAS PM-V11 BLADE FOR STANLEY &amp; RECORD PLANES 2" which suggests the Stanley and Record designs are both very close to the original Leonard Bailey design.



Hock tools say *"Our 3/32" thick blades ... will fit 99.9% of Stanley and Record style planes with no modifications other than a simple frog adjustment."



For a different sized plane Paul Sellers wrote


  Any 2 3/8″ iron, cap iron and lever cap will fit the No6. Stanley and Record will be interchangeable. It may end up costing you more than buying a complete No6 plane in the end though.


(my emphasis).