Truckabilly,
The nominal cab width of a Freightliner FLA is 94.38" excluding the lights, mirrors and grabhandles. The AMT White-Freightliner COE kit represents an early 1970's cab which was 90.38" - unfortunately this difference in width is noticeable in the width of the grille and in the front wheelwells around the tires. Freghtliner also made other changes to the COE cabs between the early 1970's and the FLA in the late 1980's. We're talking 15 to 20 years of evolution, enhancements, and new design. Changes include the doors, cab structure, cab steps, dash, shifter, heater/air conditioner, grille, and one-piece windshield opening - as well as chassis, supension, front brakes and crossmember changes (plus many that I've missed). The Italeri conventional would give you some of the pieces that were common between the FLA COE and the FLD conventional. A conversion would be a challenging but interesting project.
Hope this helps