"Jeg har tenkt mye på samtalen vår."
Translation:I have been thinking a lot about our conversation.
That would mean that not only have you been thinking about the conversation; but you have also been trying to make up your mind about it, looking for hidden meanings, contemplating this conversation's influence on other aspects of your life, thinking that if "this peace of information that you got in the conversation" could mean that something you learned prior to this would actually mean something else than what you thought at that time, what's the consequences. Thought after thought after thought...
It is okay to say, but I would be slightly worried to hear it. (I'd await some conclusion on those thoughts before settling down.)
I said 'I have thought much of our conversation'. That seems right to me
To me, to "think much of" something or someone means to be fond of them. "I thought muchbof your gift."
The problem with this translation is that it comes across a bit strangely. People don't really talk like this in everyday speech. It comes across a bit like you're a Lord of the Rings character or something :)
There actually is a word for dialogue already: dialog. The problem with translating samtale into dialogue is that dialogue is strictly between two people, and conversation has no limit on the number of participants. A dialogue is a conversation, but a conversation is not always a dialogue :)