I realize you are new to the forums, so some advice:1) read through the first page of the forum to see if your question has been asked recently.2) if you don't see it, use "search" to try and find it.
for instance, about 10 threads below yours, I found this thread, which seems to answer your questions about buying a vert.
zerothread?id=152477
There are other members with silvia conversions you could ask specifically about the conversion or you could google it, its been written up 100 times online and in just about every import magazine. as for a shop, thats going to depend on where you are and how much you want to pay.