440 rear main seal... thoughts

I’ve only built one 440 so take this for what it’s worth!! I STRUGGLED to get seal to seal. Did it three times in the car, it sucked. I finally paid up for the Fast Fish seal and NO leaks.
I think everything that has been mentioned in this thread will work for a specific block/retainer but variations in manufacturing cause the issues.
Hughes Engines has a very involved procedure and some have had success with it.
I know how you feel!!