Years ago I was employed in the disk drive industry. I agree with Nigel. Designing and building a read/write chain for MFM encoding and decoding is not for the faint of heart. IC controllers from Western Digital like the 1771 and the 1791 were a step in the right direction, but were not complete solutions.
I'd suggest you study the circuits used in the Apple II which essentially avoided what were at the time very expensive chip choices. Their approach had some problems like variable density recording, but it was good enough for the times.