Which bolts reach water jacket on 340

Post #3 is correct for the sealant. Your pump has less bolt holes because it is not a POLY.
The holes at 2-3 -9-10 o clock on your pump. (the four longest bolts).
Post #6 is correct.
Post #7 is important. If the bolts at 3 o clock and 9 o clock are to long they can go thru the cylinder wall.
All water pump bolts use washers. The pump is aluminum.
The 4 outer end exhaust bolts (studs) require RED RTV ! Front and rear on both sides. NOT Permatex! They get too hot.
Install the alternator brackets with the pump or you will be redoing two of the sealed bolts.