proper way to time engine?

Found this and was wondering if it was correct. Just rebuilt the 4300D 4bbl, replaced all the sparkplugs, stock distributor and the vacum advance seems to be working. Car was backfiring, quelled that but punching the accelorator bogs down the engine and it wants to die. Ive checked for vacum leaks, didnt see any and tried different vacum sourses for the vacum advance on the distributor.Also pulled off the EGR,cleaned that didnt see any burn marks. 351 C Q

Attach a deep socket connected to a socket wrench onto the single bolt located in the center of the vibration dampener, then rotate the bolt in a clockwise direction until the numbered lines on the edge of the dampener are visible.
2
Scribe a mark across the number “6” on the edge of the vibration dampener, using chalk. Note that the rare, high-performance 351 Cleveland engines uses different timing points, so consult the engine’s specification’s manual.
3
Loosen the single bolt at the base of the distributor with a distributor wrench. The bolt is located where the distributor enters the top of the intake manifold.
4
Clip the timing light’s black alligator clip to the negative battery post.
5
Clip the timing light’s red alligator clip to the positive battery post.
6
Clip the timing light’s third wire anywhere along the length of the spark plug wire, which attaches to the spark plug wire on the front of the passenger’s side of the engine.
7
Locate the metal timing pointer just above the chalk mark, on the edge of the vibration dampener.
8
Start the engine and aim the timing light at the vibration dampener.
9
Pull the timing light’s trigger to activate the light. Each time the light flashes, the spark plug wire that the timing light is attached to fires, resulting in a strobe effect. The chalk mark must align with the timing pointer. Rotate the distributor in either direction to move the mark, then turn the engine off when the marks align; tighten the distributor’s bolt

Looks OK except I didn’t see anywhere the need to disconnect and plug the vacuum advance hose to the distributor. You must set timing at about 600 RPM with the vacuum plugged.