I had a 70 383 with a stock dipstick that I put the 31580 pan on. It fit like a glove and the dipstick worked fine.

IIRC the tray had a dipstick cutout. It was a stock stroke.

Several people have reported the pickup hits the pan and requires reworking. Guy in here this year and I checked reviews and saw the same mentioned over the last few years. Not sure that would play into your issue, but worth mentioning.