My 316 has the relay bracket and since the M40 use M1.3 I would expect they have them to, it's a long long time since I've looked at an M40 I can't remember, same for the M42 but a trawl through the forum or Google for a picture should answer that.
I guess the iS rad could be used, don't think it's much different to the E36 rad apart from maybe being smaller.
Like I said on the other thread, I'll check whether the two types of airboxes fit the mount I have, the inner wings never changed so that can't be a reason for having the modify them
