here is a facebook piccy hope it works

[avenga]

It is a twin cam 16 valve head originally designed by BRM for Chryslers competition department to take on the ford BDA.

Basically it is a race head which replaces the standard head but also replaces the single underhead pushrod cam with twin overhead cams which are chain driven.

Most modern cars are twin cam and it allows for much high powered engines. In the 70's this was new technology so a lot of companies were getting twin cam race engines built for rally. They were usually made by race engine companies such as Lotus, Cosworth and BRM then fitted to the standard engine to increase power, usually doubling the power of the old pushrod engine.

As for price. I suspect it will be moonbeams, much more than you whole car is worth if they are making an entire head from scratch.