Hi,   I've given up trying to find a decent used lotus twin cam cylinder head and  have acknowledged the best and therefore most expensive way is to buy a new casting.  There are several retailers with varying price tags attached to their heads.  Does anyone have experience of this approach?  Clearly post purchase machine work on guides and seats is expected but to discover a need to correct casting faults is something I really wouldn't want to tackle.  Kind regards and my thanks.