Cylinder heads again:will a 535 head bolt up to a 530 Block

[canada karl]

i have been looking for a cyl head for my 76 530i. ii have an opportunity to buy an 81 3 series race car that has had a 535 motor installed in it. The car has suffered front end damage so is being sold off for less than the price of a new header. it may be worth my while to buy the whole car as I would gain a newer header as well as a cylinder head but I am unsure if the head would fit? I have read the Faq on cylinder heads but am not clear on a few things. first of all the engine is believed to be from a 535 but was installed by a previous owner so the current owner was a little unsure what it came out of but it is definitely an M30 six. any way to tell?Would this be a Motronic unit? I guess another option would be to instlall the entire motor into my 530i instead of just the cylinder head??? also the seller had a cyl head from a Six that had 74 stamped on the casting....had the early wide coolant slots .....would that fit on a 76 530i block?