torque wrench and piston question

I have a fairly cheap clicker type wrench (bought at harbor freight) Will this be good enough for rebuilding? What is a good wrench to use if not? Also are the kb107 pistons a good choice for a 360 performance rebuild, using standard j heads and a cam with these specs>>>>>>>>>>>>>>>> Advertised Duration IN/EX: 256/262
Duration @ .050 IN/EX: 213/220
Gross Valve Lift IN/EX: .454"/.475"
LSA / ICL: 112/108
Valve Lash IN/EX: Hyd/Hyd
RPM Range: 1000-5500


The only concern I have is our elevation here is 5000ft. I know I will not run as good as you guys down low but, will it cause issues?