Retubing dilemma

I have a melody el34 integrated amp.  As I mentioned in a older thread one of the tube store el34 preferred series tubes went up in flames. So now I have a choice and I want to see what people think would make the most difference sonically. I would like to keep this under  $200. 1.  I currently have 2 northern electric 6Sn7 tubes and 2 shuguang treasures 6sn7 tubes, 1 of each type on each side.  Should I replace the northern electrics with shuguangs so I have a full set all the same and just replace the el34 with the same preferred series or
2. Replace the el34s with gold lion kt77 that seem to be very well liked. 3. Other suggestions. 
As an aside if I went with #1 should I move the old shuguangs to one side and put the new pair on one side. 
Thanks