1.6 Rocker Arm Install , Lube questions

I have a running 512 RB with 1.5 rocker arms. I will be exchanging the Arms for 1.6 ratio arms of the same manufacturer. I will check the geometry and clearances as well as pushrod lengths to be sure all is good.

I have assembly lube for the pushrod cups but some say to use high pressure grease. What is best? (no manufacturer instructions from 440 Source).

The rockers have needle bearings. Most install instructions say to soak rockers for 30 minutes in motor oil before install. Is that instead of assembly grease or would your soak and also use assembly grease after all the spacing is verified and appropriate shims selected?

Finally, since I have oil up to the shafts already, do I need to manually prime the shafts by removing the distributor and using a hex rod in a drill CCW? I also have comp cams valvetrain spray lube that is for installs. (Need to read instructions again for it)

These are roller rockers and I have Flat tappets.

Any advice appreciated and welcomed.