I realized I had BES and BAS reversed when I wrote my responce late last night. I think i understand now. Looks like I will have 2 servers each running BAS only without the core stuff, each with their own SRP. Then 1 BES minus the administration service running in HA with 1 SRP. Total SRPs - 3. Am I on track now?
BAS only (no core)
server 1 - (exch-prd-bas01) - 1st SRP
server 2 - (exch-prd-bas02) - 2nd SRP
BES only (core only)
server 1 - (exch-prd-bes01-a) primary 3rd srp shared
server 2 - (exch-prd-bes01-b) standby 3rd srp shared
Many thanks for the help.