A 250 is a 250 no matter what year, they were all the same with the same heads and compression.
Depending on your fuel supply in your area, 34 to 36 total timing is about right, if you have crappy gas, back it off a little. I could never get mine to ping since the compression is 8 to 1. so set it at 35 total. I could go higher, but it didn't run any better. It runs just fine where it is, couldn't tell you what it is at idle, don't really care, thats not where it matters.
Joe
