How to change the dimensions of a curved benchtop all the way around

I had imported this bar from the 3d warehouse but have been customising it. However I want the benchtop of the bar to be 300mm deep rather than 430. Whenever I go to scale it I can get one side to 300 then the return length shortens and i can’t keep both width of the top 300 whilst making it the same length that it is.
Any help would be greatly appreciated

it would be easiest to draw a new top with the correct dimensions and replace the old…

add the link to the warehouse model or load your version here for more specific help…