Gary, you are one strong person and you will make this linear progression look like cake. My 1st attempt at linear progression on squats looked like this 225-245-265-285-305-315-325-335-345-355-365-stuck. I totally destroyed my left elbow at that point. I squatted with a safety squat bar for four weeks to allow the elbow to "heal" while I continued pressing, benching, and deadlifting.
I started up again not too long ago with a light day in the middle of the week to allow the elbow to recover between workouts since it still hurts but just not as bad following squats. So far its been 320-255-325-330-265-335-340-snowday-345-350-285.
I know you don't have the elbow issue and you have already been under 405 for multiple reps so I have NO DOUBT that you will reach and surpass 405X5X3...which is actually the goal for me as well. I just know I probably won't reach it as fast as you will given it is still unchartered territory for me.
I want to reach the 500 squat this year too and I'll be rooting you along!