Free Exam Resources
Yes! You can find 8 free practice SAT exams on the College Board site. For the ACT, you can work through practice questions for each section or download a free Prepping for the ACT guide.
The SAT and ACT have agreed on a set of concordance tables, the most recent of which were released a couple years ago. This document provides both the tables that can be used for conversion, as well as more information regarding the construction and interpretation of those tables.