The players Handbook should be more than enough for you at the moment. Though, even as a player, the Referee's Handbook will have interesting info for you in it, but it is not absolutely necessary... There is also the Frontier Explorer magazine issue #23 which has the Star Frontier races converted to the FS ruleset which I will also allow.
If you do Dungeonslayers I will 100% beg to join your game. One of my all-time favorite systems. I'm pretty sure I've played with you on here and other forums in the past.