G60 = 8:1 c/r
16v = 10:1 c/r
Any knowledge you have of fords is worth chocolate when attempting to do stuff with vw engines unfortunately.
If like you say you want to "bolt on" a supercharger then the simplest way is with a 16v/sc integration kit from bahn brenner
http://www.bahnbrenner.com/media/php/catalog.php?pid=625&catid=169 . You will also need..
16v Scirocco upper intake manifold (good luck finding one)
G60 G-Lader Supercharger or BBM Screw Compressor Supercharger kit
G60 G-Lader mounting brackets and belt tensioner complete
G-Lader outlet (silencer box) or BBM RSR outlet kit
G60 Serpentine / idler pulleys for water pump and alternator
G60 AC pump or European water pump pulley
G60 Throttle body, complete
G60 Fuel Injectors and FPR
G60 Idle stabilizer valve (ISV)
G60 Digifant1 ECU and engine wire harness
G60 Digifant control relay
G60 Oxygen sensor
G60 Water temperature sensor (blue)
G60 CO% potentiometer
G60 Relays, fuel pump
G60 Intercooler, IC hoses to and from the G-Lader
G60 Lower water pump pipe
Upper and lower coolant hoses
G60 Radiator and fan assembly
lowering the c/r can be done with a thick head gasket (risky) or custom pistons.
probably easier/cheaper just to do an engine swap, or start with a G60 engine complete.. or dump the g-lader idea and fabricate something totally custom.