Just as an aside, if you look under the left side of the engine, there are bolts that have copper washers under the heads. Electrolysis has never been a factor on engines, even in cooling systems, as long as the proper coolant is used.
I usually replace soft sealing washers with Stat-O-Seals, which are steel washers with a Buna-N "O" ring bonded to the inside diameter. They don't crush down, and last almost indefinitely.
10 Duc Streetfighter S (black)
67 Triumph Bonneville TT Special