You will need to rerun the checkout wizard to create the paypal checkout pages. In the cehckout wizard, on the last step, make sure to use unique names for the pages.
you then need to add a link on the cart page to offer the option to checkout using paypal.
Using paypal pro, they will be able to checkout using a credit card similar to Link Point, but also using Express checkout where then select to use their paypal account.
using express checkout they go to the paypal servers to select the payment method and shipping address, then they go back to your site to see the final cost including shipping calculations to confirm the order.
Any customizations you have made to the shipping lookup for linkpoint, you will need to redo for the paypal checkout.