It depends on the actual workload, I would say. A SQL VM can be idle, or very busy.
The amount (capacity) isn't so important unless you enable inline efficiencies n SSDs.
Since you have some indicators about CPU utilization from existing deployments, you can see (or do a PoC if you can't get real data) if 8c (4c physical) is enough or not. It's a small environment so I'd start with the minimum OTS hardware requirements.