You are almost talking in circles and making it WAY more difficult than it needs to be. The fact is a poor 60' hurts your run. It hurts the 1/8 and it hurts the 1/4. Improve your 60' and your 1/8 improves as does your 1/4. There is no denying that. I already said the conversion isn't an exact science, but its close enough to get an idea.