Originally Posted by gvasquez_81
i heard that you run into the risk of ruining them. Just something about drilling the heads seems not right to me.
"...something about drilling the heads seems not right to me". Because it's not right to drill them.The problem isn't so much that you may hit water- you WILL hit water. But the casting isn't thick enough to always support the load the brackets put on them, and the head surfaces aren't always flat so alignment can be off. People have done this and gotten away w/it- but there are a lot who regretted not doing it the right way from the get-go.
The easiest/cheapest way around this is to swap over to the ('68-back) short water pump set up. The only snafu is the A/C compressor used back then was the big old A4 type. If headers are used there are different brackets from the aftermarket that need to be used for the alternator, but these are cheap. Custom brackets that don't require the head accessory holes will also work, but are expensive and I personally do not care for their looks. If custom brackets were the only option, Vortec heads are looking more affordable, besides making more HP than any of the other heads you've mentioned.