Originally posted by outlawz
At first thx at all

It is a 400 er Small Block no Big Block.
Yes I have the Original Heads .But I read that Chevy Heads before 1974 are not so good.
I can get some used old Heads from a 350 for a low Price.
Some Power in my Engine will be fine but the important thing is to drive it every Day without Problems. Gas is very Expansive (like everything in Germany) and it will be fine to ride with low Octane
Unless someone has added them since the 1969 400 heads were produced at the factory, they will not have hard valve seats to contend with the unleaded fuels which are available today at the gas pumps in America. I don't know if you can get leaded fuel where you are.

1973 and later heads will have induction hardened seats and will be compatible with unleaded fuels unless multiple valve jobs have been performed on the heads, thus cutting through the hard material.

The 400 heads which you have can be upgraded by having them machined and hard seats installed, or you can use 1973-up 350 heads with 76 cc combustion chambers and have the same thing, except that the 350 heads must have steam holes drilled in them in order to be compatible with the 400 block. (use a 400 head gasket as a pattern).