stock is 7mm which is fine. 8mm is ok if they don't cost too damn much. 9mm is just a waste of money.

depending on how old your water pump is, since the top of the motor is stripped off, i'd consider the front - water pump, wp bypass hose, timing set and gasket. timing set sounds like overkill, but the timing cover is part of the water channel, and prone to develop leaks over time. in typical dodge wisdom, since you have to remove the balancer to remove the timing cover to replace the water channel gasket, then **** you might as well replace the timing set since you're looking right at it.