If you can't make progress with your own work, you copy. Works every time!
The chassis is good in my eyes. It is very modifiable.
Here are a few things i would change on this car:
[*]Wheel base, it may need to increase to allow for:
[*]Changing radiator layout to the typical slant down layout, which does take up more real estate but with a longer car that's not an issue.
[*]with lower, more aero efficient radiators, we can now reduce side pod height and lower radiator exhaust exit size. Bring down the sidepod shoulders, round them a bit and lower the outlet and flatten the top area of the engine cover over the gearbox.
[*]Make a new front wing with elliptical profiles like what redbull have been doing for the past 4 years.
And there you have it. An improve Mclaren. All these things are what i visually discern anyway. So from this i would say they have a large scope for improvement. And they can do it. Mclaren are known to bring bigger bodywork changes to a car than any other team.