I am searching for a method to have of my single publish pages (single.php) show the entire size image no matter the custom dimensions i have published for home index page.

Among my many tries and fails cleaning it once a this featured image solution however it did not actually work for my reasons. http://voodoopress.com/2011/04/woking-with-featured-image-in-wordpress/

It is possible to wordpress plugin with this that maybe I'm not sure about?

My PHP understanding is restricted as you would expect. It is possible to php code will be able to put in the only.perl file to achieve this?

Any assistance is greatly appreciated . Thanks.

You are able to pass a size parameter of 'full' towards the the_publish_thumbnail() function such as this

<?php the_post_thumbnail('full'); ?>