You ask what do we think.....as most state, your car, do what you want but here are a few thoughts. Being a '73 it will never have the value of the 70-71 and even though these models have some different styling most of it comes down to personal preference. The cost to change the appearance to an earlier model will be significant & in the end you will still have a '73 so IMO unless these things would have to be replaced anyway, esp. tail panel & grille, the cost may become prohibitive......
Have fun with it & don't worry about what everyone else thinks, your the one that should be satisfied.