Torque plate

Understood. How long ago was that? Did they own a good profilometer?
I've built engines that were plate honed, but when measured the bores were straight and round all the way up to the deck without the heads in place. There should be a measureable distortion without the heads if it's done properly. The shop I use bores with the main caps torqued but no deck plate, using one or two passes depending on the amount being removed to within .002 of finish size (Rottler F86A CNC mill so feed rate and spindle rpm is completely adjustable). The rest is taken off a little at a time by the honing process.

To expand on what you said about honing - honing takes the sharp edges left after boring off the cylinder wall surface and preps that surface for the rings to seat quickly and seal. While it does remove material, it's less and less with each pass and there are course and fine stones and brushes which when combined with the rpm, speed of the stroke, and pressure on the abrasives get the desired finish for the rings you want to run. It's not really a "pass" but a series of strokes with varying grit abrasives, varying speeds, and varying pressures on the walls. When it's all said and done properly the bores will measure tighter and out of round at the top where the bolt bosses are cast.