speed for 4130

Hello, I am going to be machining some 4130 plate. I will be using carbide cutters. I have the program running at 60 SFM.My question, the program says it will take 4 hrs to run. My problem is that I only have 3 hours to run the part. Whats the fastest I can run the tool, or would I be better to run hss to rough and carbide to finish? Thank you.