Hello Erick,
Here are some misc. facts;
The compression is the same on both the USA and Euro heads. The head gaskets are even the same. The early and late heads use different head gaskets on both Euro and USA versions. Any significant power gains are related to the camshaft only. Early version 280SL engines were the same as the Euro versions.
The BBB makes no mention of significant variations of the two. I suspect the difference may be something external. Possibly the attachment point for a emissions related sensor?? The USA head on the later cars supposidly carried the "280SE/A" designation.
Joe Alexander
Blacklick, Ohio
