Creating a Scheduled Process for New Accounts in CRM

Can anyone give me advice or point me to solid resource about creating a scheduled process to regularly search for 'new accounts' that are 'not already in my CRM' (where that CRM list is more than 50k records)? Goal: Check Clay for Accounts in our ICP every Saturday, then enrich and import back to CRM Challenge: I want to exclude records in our existing database of 100k records, but can't figure out how to import a list of 100k from SFDC (I don't see a way to import a List, but exclude the first table with the first 50k) NOR can I can see a way to exclude 2 lists in the Exclude companies feature even if I could Hacky solution: Don't worry about 'Exclude Companies' but build the ICP list and use a Record Lookup within the table to search for matches and only enrich & import when the SFDC Match fails Has anyone solve this more elegantly or am I on the best track?