Thanks @tpoterba. I later figured that out and was able to increase the # of executor cores but unfortunately I am still getting SparkExceptions on this PCA run.
I have created a new line of inquiry at PCA job aborted from SparkException so as not to sidetrack this older thread.
Do you think the issue is in Spark configurations or in the cluster resources? I am currently running with 24 nodes (12 of which are preemptible) but I am experimenting with increasing compute resources even further.