Like said above, it works fine. I do A LOT of Hp marine engines, Mercruiser HP500 502's are like a## holes, everyone has one, and they all have 088 heads on them. I have right now 5 sets of take off heads on the shelf, and will do them up from time to time for a budget bracket deal, and use them on a Mark4 block, you just need to use a gasket intended for the Gen5 or6. The gasket will match the heads water ports, which are way different than the Mark4 stuff. The water holes are in the right spot on the block, so, it doesn't matter what "printo seal" is on the gasket, it will just seal on the flat deck. It works fine.