Engine Pushrod Length?

Getting ready to put GT40P heads with 1.6 Roller Rockers on my fox. I've been told my engine has a "mild cam" but no previous owners know which model. I would assume a B cam is most likely. I've heard guys say they run 6.250" (stock) pushrods on these heads with a stock cam, but with an E cam they needed 6.300". I'm hoping to not have to measure and set the project back since I'll be swapping in the driveway over a weekend.

Has anyone run this setup? What length pushrods did you use?

Thanks, Clark.