Thuja Plicata Pruning Question
 

I have a row of neglected Thuja Plicata conifers which are approximately 20 years old. I have been told that I could prune these at the base to recover some of the ground space lost by the growth, and that pruning could be quite severe - 2m in height and up to 2m in towards the main trunk.
Others have told me that hard pruning (back to brown bark) will permanently damage the trees, while others say that recovery is possible (i have been shown growing shoots deep inside which I am told will flourish once exposed to sunlight.
Can anyone clear up this confusion - would I damage these lovely trees, or will they stand hard pruning as described?CGITSMDEV01