I am wondering if there is a good resource for finding general guidelines regarding omega 3/6 ratio in foods.
For example, I know that beef is supposed to be higher in omega 3s than chicken (especially grassfed), but by how much? Should I avoid chicken or chicken fat, or just show a preference for beef?
I take fish oil, but would like to be able to rely on my diet more for optimal 3/6 balance.
In terms of common meats, beef is the best (20% fat, 0.4g o-6), lamb (23.4% fat, 1.3g o-6) and pork (21.2% fat, 1.6g o-6) much the same and chicken (8% fat, 1.3g o-6) far the worst. Turkey is about the same as chicken in terms of ratio, but it's so much leaner that there's far less omega 6, as there's far less fat. I'm basing all of these assertions on www.nutritiondata.com mentioned above, to compare you need to guesstimate which cuts of meats are comparable though (hence going for ground meats).
Elsewhere on here, the NutritionData data about grassfed versus conventional meat has been challenged, on the basis that ND suggest that grassfed beef still has substantially more omega 6 than 3, yet (it is argued) that given the nature of grass, pure grass-fed beef couldn't end up with much more omega 6. On the other hand, even 'grass-fed' animals tend to be fed something else during the winter and even those fed on grass-concentrate end up with a disbalance towards omega 6 (very limited study though since the animals were only fed on the test diets for 85 days pre-slaughter).
Here is a link to an article that begins to address your question. You can use this service to do an analysis of any food you would like to eat.