Ceramic coating works brilliantly... Want to test it (and stuff your engine in the process), get a spark plug, crack the ceramic around it and drop some in one of the chambers, it'll just rattle around and gouge a groove into your block... I've seen it happen
If you do go with ceramic or TBC spray stuff, make sure you coat the chamber and the piston, pretty much everything that's going to come into contact with the head of combustion (Event the head/valves if you really really want to) to prevent hot spots forming around the chamber where it doesn't have the coating. The 4AGZE pistons are ceramic coated, and work brilliantly at head dissipation, but it means the block itself heats up more.
Personally I've only ever seen the cylinder bore and piston/con-rod coated, and it works brilliantly, just the head/rocker cover gets very hot in time... If you do go down that way, let me know how much it costs you and how well it works, as I'll be exploring this for my car in the near future