Don't put seals under the doors. In 1990 I put new repro ones on and couldn't close the doors, so for 20 years, I've driven my 1958 TR3A over 105,000 miles without them. I'd guess that it rained about 4,000 miles during those 20 years of driving. Never got wet from down there. I don't drive in deep puddles, in snow or slush of any depth and no TRA or VTR judge has ever docked me a point for them not being there.
The cross-section of the repro rubber seals to too big - so leave them off. If you think you will feel a windy draft coming in where they should be, just think about all the wind hitting you from above the door.