I don't know if will help, but I was looking at 5.3 heads, so I emailed Texas Speed to check their port only pricing-here is the reply.
Jeremiah,
For cnc portwork, valve-job, and milling we charge $750.00. To upgrade to larger stainless steel intake and exhaust valves we charge an additional $200, and to add a PRC .650” dual spring kit it adds an additional $250.00. If you have any other questions please feel free to email or call.
Thanks,
Jake Keeling
Texas Speed and Performance
Jake@Texas-Speed.com
806.698.0365