Shelby;
With a hydraulic cam,you need to keep the rpms up around 1800 to 2000 for the first 20 to 30 minutes of running,since you now have 300 or so miles ,I guess you are long past that point.....
The way I did my 351-W and this way was recommended by most engine builders I know was,intial run,20 minutes at 1800 rpms,shut off,let things cool off for a few minutes,change
oil and filter,cut open filter,look for debris,parts,shiny fine metal,etc.etc,start back up,reset timing,carb,then I ran it for the first 300 or so miles not exceeding 4000 rpms (my own personal limit),changed
oil and filter again,cut open filter,check for debris,metal,etc.etc,. Everything looked good,run it like you want to (I limit mine to 6000rpms).... Now have about 21,000 miles,30 to 40 1/4 passes,300 or so miles at "open track" events flogging it pretty good and the motor has run flawlessly,does not use
oil,nor does it leak any oil from anywhere,thank God..... With a little luck it should last for a long time to come..... Using top notch parts does not hurt either especially if you plan to do some performance driving......
David