Hi Dave, firstly welcome to the forum! Your BIS project sounds interesting, it would be nice to put a picture up on here!
There are various companys, who will drill the correct stud pattern into your alloys, to fit your BIS.
Other wise here is a site with some info on various fiat alloys! Laot of people like the x1/9 alloys, including myself. They can be easily found on the net.
http://www.mirafiori.com/dave/s-wheels.htmlHere is a company, some one recommened to me! (Im not advocating that this company is trust worthy etc, as i have not used them myself)
http://www.tyresave.co.uk/alloyskn.htmlI hope this info has helped a little john, You want to speak to "Maxlee" and "Slater", "FiatFSM" "PaulHarbinson" "Stuey" who are on this forum, along with everyone else. They all have much more knowledge on the subject!!
Kindest Regards
Chris