A 450X is (at least used to be) the closest thing to "a 450R with lights." They were also detuned and heavier. As I recall, one tooth on the timing, smaller headpipe, heavier muffler, bigger radiators, carburetor, gearing, wheels, suspension settings and I can not remember too much else. The X was delayed quite a while because Honda did NOT want it to be a 450R with lights. There are many, many parts that do not interchange between the R and X, and Honda spent a lot of time and effort before they released what was for the most part a completely new motorcycle--the X.
If the new 450L is indeed a 450R with lights then Honda has completely changed its approach to these machines and it would be a great surprise to me--and I was pretty close to Team Honda and their off-road development team, at least in those years.