cooling sys???

hi guys going through the hull before installing new ingine and pump my ??? is this the hose coming from my pump to the mtr it looked to be 1/2'' in diameter coming out of pump then goes to a 5/8'' hose to a t then more 5/8'' hose to the water pump cover where it goes back to 1/2'' fittings in the cover. what i want to do is go steel braided line can i use the same size line or do i have to have the two different size hose i do have a valve coming off the pump. and what size should i use?? the water lines for the headers are 8's just did those last weekend thanx ralph