love-dat-bottom-end

I have been working on my 440/650 conversion and was thinkng about dual cooling. In order to get more water flow would I need to swap my current hose that goes throught he bulkhead with 1 larger hose and split it off when i gets up past the bulkhead, or run a new line through the bulkhead so i have two. Any more info or input on dual cooling or extra cooling mods in general with opinions would help out a lot. I dont want to do more than what is necessary but would like to get some gains. A diagram of lines and where they run would be great if someone has one (especially with cooling to motor, head, and exhaust.) thanks