The 1.8 engine I was refering to was the european 1.8 mk3 golf. Which is a steel pulley unlike the GTi which has an alloy pulley.
I was having a think, with regards to the tracker stuff, would it not be easier to use the water pump pulley from the tracker (get a golf GTi one for your current engine) and bolt that to the crank? I have the odd feeling the traker water pump has a 4 screw fitting anyway, not sure if it lines up with the vw holes mind. Then you would just need the V-belt accessory pulley. alternatively have you tried the 4 rib on a 5 rib pulley? it cant hurt to have more ribs than you need!
As for offset, this is something to be ignored to somewhat with the accessories your fitting as you can make the brackets to suit the offset you need.
So really you just need a crank/waterpump pulley from a TDi mk3 golf or something?