I am working on a similar project but based on a 69 SR shell. I have bought the following parts : 01 explorer spinles, cv shafts, front différential, awd transfert case, 4R70W transmission. the engine will be a 4.6L cobra engine with a Eaton supercharger. I have all these parts in my shop. I am still wondering if I ll go for a cobra IRS or a solid explorer rear axle.
to my knowledge, the engine has to be moved a little on the passenger side and the transmission tunnel widened. I will build a separate chassis and I am still looking for A-arms ; the negine will also be set back for weight distribution
awd are the best cars on the road, since my unforgettable Audi S6 quattro, I am working on building that project.
good luck with your project, sn mustang are plentiful and cheap so if your project is well thought, it won't be that expensive. ( I am under $9000 including the engine and 69 purchases)