Vitus 979 downtube shifter fixing problem

[Ideale]

This Vitus bought from forum member has different shifter bosses to 2 others I have in that it seems to already have the curved radius shifter boss cover in place as part of the braze on- this means that a standard shifter with curved base won't fit.(Shimano 600 in this case)
Can't quite work this out- does anyone have any ideas please?
Thanks
Now answered-thanks!