Cool trip, and takes some guts. I liked the customs-episode, when you noticed the alphabets and phrases missing, that's hilarious. I have visited Murmansk couple of times with a car, and here is a local joke: "How was last summer ? I do not know, I was working that day." I've traveled Baltic countries couple times with 25 year old sports tourer, and a solo tour in Poland/Belarus/Russia is next summer's plan. Just like your grandfather, my father was visiting Russia in 40's, but with a machine gun; I was first from our family to go there unarmed..
Luckily things are different today, and normal travelling among friendly people is now the case.