Another option for the image width and height would be to use the default "SMALL_IMAGE_WIDTH and SMALL_IMAGE_HEIGHT" That way if you do have calculate image size set to true the images will scale.
If you want to try this; open includes/modules/link_listing.php
find the following line of code (at around line 93)
Code:
$lc_text = '<a href="' . zen_get_links_url($listing_query->fields['links_id']) . '" target="_blank">' . zen_links_image($listing_query->fields['links_image_url'], $listing_query->fields['links_title'], LINKS_IMAGE_WIDTH, LINKS_IMAGE_HEIGHT) . '</a><br /><a href="' . zen_get_links_url($listing_query->fields['links_id']) . '" target="_blank">' . $listing_query->fields['links_title'] . '</a>';
replace LINKS_IMAGE_WIDTH with SMALL_IMAGE_WIDTH
replace LINKS_IMAGE_HEIGHT with SMALL_IMAGE_HEIGHT
save the file and upload to your server
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