Thanks, I appreciate you sharing your knowledge!
I tried to order the perch kit via ******************************************** but it was "no longer available". Other merchant quoted me outrageous ($200+) shipping fees - obviuosly nobody wants my business!
Also, nobody on my side of the pond seem to sell this.
On top of that it seems that the GT3 perches I thought was an option really wasn't since they run 60 mm ID springs. Go figure.
Back to square one, then!