Rocker box differences

[mark]

I have just discovered that the rocker box I had planned to use on my alloy head is from an iron head and doesn't clear the valve springs when fitting. Some research told me that the alloy head boxes were modified with extra clearance and the casting number was over stamped. Has anyone modified the iron head box to suit the alloy one?
Mark

[muskrat]

G'day Mark,
                    I just picked up a proper one on ebay. It has 67-1142 over stamped the cast #. It is a little thinner at the rear and front corners. Untill now have only had the std box's and it's a bit of a wiggle but they do go on. I will take a couple of pics tomorrow and post.
Cheers

[magicflem]

I also purchased a rocker box no. 67-1142 from Ebay and yes, it is a bit of a tight fit.