Answer:
There isn't a conversion between the two. The SAT I is the standard math, reading, writing test, which is required for most colleges. The SAT II, know as SAT Subject Tests, are one hour tests in one subject only. These tests allow you to show your strengths in particular subjects - especially the sciences and foreign languages as these are not tested on the SAT I - but most students take them because some colleges require them. SAT II scores have varying curves depending on the test, so conversion to SAT I scores is impossible.