A 360 should be timed with the cam dot at 6 o'clock and the crank dot at 12 o'clock so the dots are as close together as they can possibly be, now a Gen3 Hemi is timed the opposite way with the cam dot at 12 and the crank dot at 6. Cam timing wont necessarily cause leak down at TDC but will cause low compression as the intake vales close to late after the piston has already started moving up the bore before the air is closed off essentially reducing the effective stroke.