Outboard/Stern Drive with Hydraulic Steering
Hydraulic cylinder < 15 cubic in or 250cc RPU80 NAC-2
Hydraulic cylinder(s) 10-33 cubic in or 160-550cc RPU160 NAC-3
Hydraulic cylinder(s) 17-58 cubic in or 290-960cc RPU300 NAC-3
The above is from the Simrad website. Since you have 2 rams with capacity of 16.6 + it looks like you should go with a NAC-3 and an RPU-160 pump. If you only had 1 ram you could probably use the NAC2 and RPU80. I have a grady with twins but only 1 ram and the AP2403VRF with no issues.