It is very advisable to discontinue running the newly rebuilt 216 until you are able to run the engine at 2,000 RPM for 20 minutes to properly break in the new cam (assuming that cam is new).
The cam lobe/lifter contact areas are only lubricated from oil splash. At idle, the amount of splash is not enough to protect the new cam until it is broken in.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission