Another thing to consider here when setting up a brand new distributor from scratch: Vacuum advance setting. You need to check/set this and you can actually use your timing light to test when the vacuum advance kicks in - but, you need a vacuum pump/gauge.
Vacuum advance is supposed to kick in at 102mm (4in.) HG. When I setup my new distributor, I attached a vacuum pump/gauge to the vacuum port on the distributor and used my timing light. I used the pump to slowly create vacuum and watched where the vacuum gauge was when the timing mark started to advance. My distributor did need some adjustment to get the advance to kick in when the vacuum was at 4in.
1968 Series IIa
1997 Defender SW (Original Owner - Sold)