You are not worrying needlessly - pedal strike in corners will be a real possibility and a source for added danger and excitement - if that's what you are into.
I look at this as just one more reason why your project is a bad idea - the main reason is that, judging by your comment about getting a longer seatpost, the bike does not fit and was nto designed to fit an adult - even a short adult.
There are literally tens of thousands of old Raleighs sitting quietly in people's garages all over the Western world, and the Women's step-through frame models are as common as the men's, in my experience. I'll bet if you put a WTB ad on your local Craigslist looking for old Raleighs you will get a few responses... There will likely be Raleigh Sportses, Superbes or (if you are lucky) Twentys (20" wheel FOLDING!!!!)
If you are determined to go forward with the kids bike, good luck, and watch that pedal strike - you may wind up on your arse in the middle of an intersection at a very inopportune time.