Can someone post what head gasket and manufacturer to use? I have read different opinions on this topic with the MarkIV block & Gen V head combination. Some say it does work and some say it does not work. For those who have been successful, please inform. Also, where is the water passage hole drilled that is mentioned in past posts? (I do not have the old head gaskets for reference.)

we did do this on a 454 mag in an emergency.it didn't look like it would hold up because there was very little gasket in some areas.we had a machine shop drill the heads and get us the gaskets.the last i knew it was still running fine two years later

I have not done it but this should be an easy check.

Set the head on the block without a gasket with a couple of bolts. Look at the water passages in the head at the intake valley area of the block.

The water passages in the head should overhang the lifter valley. If not be too close to seal off. You can even trace the contour of the block on the head, lift it off and see how close.

I guess it is possible to get a block/head combination that would work.

I've been running this combination for many years.... I have used a hole punch to put the hole in the gasket (but I had an old gasket for reference. Mar4 block, Gen 5 magnum heads.

To my knowledge you cant put 5or6's on a 4 block.You can do the opposite with a 17046 fel-pro for 454 and a 17048 for a 502.

That's not where your water leak came from is it?