As said start w the OE location which is front/rear parallel (BB) or at front DR intake manifold bolt (SB) & even tho it can b clocked anywhere if you route the plug wire order to match it (wherever the rotor is that's #6 if you're dot to dot (12/6 o'clock on the tim gears) and the best( by far) is to locate it where it will place #1 plug wire in the OE location which lets the plug wires nestle neatly & lets the wires b the shortest and maintains factory standardization which is rotor position for #1 forward and slightly to the pass side (SB's) which'd place #6 rearward & slight to the dr side. Not sure on BB's as been only on SB's for decades. Be aware that some dizzys have a diff bottom tang to top rotor locating slot phasing