Ok so I setup the weight based shipping and a price based shipping as instructed. Also the product I want to offer the free plus shipping option contains a weight based value.
1. When testing at the checkout if I have the corresponding number of items that total the value to offer free global shipping along with a free plus shipping item the free global shipping over rides the free plus shipping option.
2. If I have a single free plus shipping item in the cart and proceed to checkout, the option is given to to use the standard shipping rate.