Badlymad,
I went ahead and replaced the main image for the Cadillac Funeral Coach since it looked like the original was simply a zoom/crop of the same frame of the movie. But I hesitated to replace the original images of the LTD Country Squire and Gran Fury. Though the captures you provided are obviously higher quality, I kind of think the originals show a better angle/view of the cars.

I have heard it said on the site before that it is preferable when replacing pictures to use the same frame of the movie (unless there is an obviously superior view available). So if you could provide the higher quality captures of those two, I think it would probably
be best to upgrade with the same. As always, you can post the extra images in comments yourself.