Hi Andrew,
Hope I'm not treading on too many toes regarding QCTPs, while I can see advantages for them in some instances of personal preference, the 4 way toolpost has served me well for many cherished years...
The 4 way toolpost on my Colchester Master 7-1/2" has been refurbished a couple of times by myself, mainly to accommodate my liking for preset height tooling...
Right from the start I dismissed the practice of shimming...
I found 16mm square toolholders to be the requisite size for this 7-1/2" CH lathe...
So made preset blocks to take 16mm tools to correct CH, even made allinone Parting toolholders, and other profile tooling at 16mm..
Then loaded the 4 way with whatever tool I required to complete the job in hand, and had the convenience of being able to select the right tool just by rotating the 4 way to its positive stopping system...
Coupled this to my system of carriage stop setup, I could efficiently do repeat jobs if needed...
Below are a few pics of bought and shopmade tooling...
The round(RCMT) tools were made handed with the option of mounting the tip either top or bottom to facilitate LH or RH...
As a sort of PS. if you haven't the facilities to make the preset tool toolholders then this reply is sort of pointless and I apologize in advance...