Replacing a lazy lifter

Yes, you need to get up to the 2000+ rpm range to ensure that the lifters are rotating in the bores, 20 minutes is sufficient to to properly break in the lifter to the cam lobe.

The worest thing you can do is let it idle or let the rpm drop enough so the lifter stops turning. You want the ignition timing as close as you can get it so the engine will start right up. Also if the carb gets drained fill the bowls so you aren't cranking waiting for the fuel pump to fill them.