compatibility

A query for the knowledgeable? Will the 24v cylinder head which featured as an option for w124 300e petrol vehicles, the 300e 24v fit a 12 valve block. This unit is stated as giving some 30bhp more than the standard 12v engine ok its high up the rev range but still a worth while power gain. Has any one tried this? Or has anyone tried the TDi engineering supercharger conversion, I have asked them to put me in touch with those that they have converted but they cite data protection. Shame, this conversion claims to improve the 12v engines output by nearly 80bhp at a cost of approx £5000 plus vat fitted, giving almost V8 power. But I do want to speak to the converted in case there are issues. Now that my engine is healthy and my brakes are tip top I want more power so any sugestions? I have fitted a K&N and lost the 2nd silencer on my exhaust already.