Also on the Zeeker heads,you need to plug the 1/4" oil hole and drill it back out to about .060-.080. If not it will fill you valve covers full of oil @ about the 1/8 mile mark. Todd Marsh done a set for us 2-3 years ago he may can help you out with them.
The Zeekers I had were the raised exhaust ports same as the Indy 440-1 heads.

The cracking the Zeeker heads(on most anyway) were from being ported. The thickness(all the same thickness) of the casting were not the best on them. But most head porters knew this and did not push it to the limit on opening them up.