Do you have a standard/deluxe tank lying around in reasonable condition (I don't care about the paint but would prefer no dents)? Do you want a part off a GL500I Silverwing? Maybe we can do a swap? Or just let me know how much you want for your tank.
Have a look at the parts listed below or I might be able to take off other parts that aren't listed (side covers, h-box...):
F/S: GL500 Interstate parts
'81 GL500I Silverwing --> something cafe racer-ish (work in progress)