AS far as I know
stage one ----matched ports/minor combustion chamber polish
stage two ----polished matched ports&combustion chambers modified & double valve springs
stage three---- as above with larger valves/full polish/ enlarged ports cc'd & flow tested
as for cams there is realy no stage 1-2-3 ect as ther are hundreds qf different grinds to suit all types of aplications-rev ranges torque curves ect, the terms stage 1-2-3 came about in the early 60's when here in Australia every young bloke was fitting twin carbs & extractors and wanted a cam to suit so when they went to a speed shop they were sold a "stage one"triple carbs minor head work got a "stage two" bored out/fully mod head/balanced ect got a "stage three"as this way the shop only had to stock three grinds for the most common motors ie:holden/ford/bmc
in Wade cams if I rember right the 104 was stage1-113 stage2[most common for usable street use] 121 stage3 you then went to some very wild grinds for drag racing/hill climb/circuit racing,you can get a cam ground for any aplication you just have to let the suplier know exactly what mods have been done and what you want the rev/torque carictaristics to be
Russ [ex Wade cam grinder]