Hi Mike,
Cameron dropped me a PM last night with some questions and I sent him a lot of the same links as you
He is registered here on madabout as well, so maybe he'll be along later to give us more info on his build. I can already see he has a very large garage that is well organised and he has the first Sportster I've seen using the complete e39 rear suspension.
I think his engine is an M52 or as you say maybe an M54. The main difference seems to be the electronic throttle cable. He certainly does have dual VANOS and the M52 type inlet manifold with variable length tracts. It does mean the inlet manifold sticks out more than the M50 manifold.
I suspect his offset engine mounting is deliberate but thinking about it, a call into Marlin wouldn't go amiss to confirm since they do occasionally ship the wrong parts.
I also suggested he contact Mark about disabling the immobiliser but I think there was that guy at Stoneliegh that knew someone who could do the necessary. (John from Warwick?)
Maybe Timbo can now help??
I think there are now a few examples of re-mounting the alternator (yourself, Ian (Morris) and NigelB)
I think his biggest challenge will be mastering the electronics.....should be fun
I wonder if Marlin supplied him with an MBM servo??
...peter