IMHO, that 888 is worth less than a standard 888, a car such as that should be standard, as 888 intended.
I do know what you mean about the SC conversion though, I couldn't warrant spending £5k on my Vectra, just to take it to 240bhp.
If I had the kinda hp in mind, I'd stick a LET in it for £1.5k, and be done with it.