Got a set of Magnum Heads

I had a chance this week to go to a local U Pull it and found 95 Dodge Van with a 5.9 Liter in it. Took me forever to get them out but I got me a set of Mag heads.

One question I have though. I have an 86 318 with 302 heads and when comparing the 302's to the Mag heads I noticed that one of the water jackets in the middle of the Mag head was bigger than the 302. I didn't measure it but it seemed to be almost a 1/2" bigger (longer). Is this anything I should be concerned about?

I am at work now and can take some pics and post them when I get home.