oil capacity question

I'm so close to starting my 340 for the first time. This is an exciting time and a nerve racking experience at the same time, especially if you have OCD like me. I have a Milodon 30935, 8 quart oil pan, as well as, a 90* filter adapter, and running a Wix 51515 filter. I used my trusty ol' pressurized oil pre-luber to run 8 quarts through the engine @ 60 psi while turning it to fill all the passages and rockers. I let out a sigh of relief when I saw I had really good oil flow coming from both rocker shafts. Then when I checked the oil level it shows I'm down 1.5 quarts. Does this sound right? I don't want to just add the difference before I get some advise, this royal purple stuff is expensive lol. Thanks