What’s a 360 worth

I would negotiate for sure. That’s a typical price range but you can find them cheaper sometimes. What I found it varies by location. I would need to know the history of it, Standard bore? Why was it taking apart? Did it spin a cam bearing or crank bearing? Has it been over heated? Does the crank look useable or does it need grinding/polishing. I would start around $200 and work up to what you’re comfortable spending for it. But hey $400 no haggle is not terrible if they are in fact good parts.