383 Correct Distributor Install?

First engine must not just be at "TDC" it must be on the COMPRESSION STROKE. There are two ways to verify this.

1...Easiest (usually) and most common is to remove no1 plug, bump engine until you feel compression, and then continue to rotate a short distance to bring timing marks up

2...If either valve cover is removed, bring marks up to TDC and look ate either no1 or no6 valves. Whichever pair is closed is ready to fire.

I don't know about B/ RB but on SB engines, not all dist. drive tangs are located relative to the rotor in the same spot. The engine will run in time with the rotor pointing 'anywhere' so long as the no1 plug wire is plugged into whatever tower the rotor is coming to.

At one time caps were marked as to "proper" no1, see this thread

Where is the rotor on a 440 supposed to point when at TDC on no. 1?