The College Board has just released updated concordance tables so that students can compare scores from the ACT to the SAT. Students can also use the tables to compare scores from the old SAT to the new SAT. Here is a link to the new tables:
https://collegereadiness.collegeboard.org/pdf/higher-ed-brief-sat-concordance.pdf
The college board has also created an app for smart phones that converts scores among these different tests.
Use these resources to compare your scores to determine whether the ACT or SAT is a better fit.