Hard to choose between the two cars. I was in the same dilemma myself, but opted for the G60 as the MK1 felt a bit gutless in power compared to the G60. But it's all about the character, and personal choice.
To check if it is an original G60. The rear panel (above the spare wheel as you look in the boot) has a VAG sticker which gives all model information. It should say G60 on that sticker. The same sticker should also be on the first page of the service book "if he still has the original". So you could match it up to that.
Edition one G60 specification:
Colours: Metallic Quartzite (Pearl Grey), Dark Burgundy Pearl (Aubergine) or Black metallic.
An "Edition One" sticker on the corner of the bonnet
Removal of the red GTI trim around the radiator grille (Black grill)
BBS RM012 two piece split rim wheels
Round "Wolfsburg Edition" emblems on the wings instead of the side repeater indicators
Mirrors painted in body color
G60-spec wider wheelarch flares all around
Partially darkened tail lights
Front white indicators
The VW logo on the back in black
Power steering with four-spoke steering wheel
Gearlever knob and handbrake grip covered with leather
Mauritus Blue interior trim with matching carpet, door cards and boot area.
Embroidered RECARO sports seats with electric height adjustment
Chromalux glass on the rear side windows and rear window (Slightly tinted)
Power steering
MFA
ABS
I might have missed something, but it should get you started lol.
