Hmm, it's hard to say whether or not this could work without seeing his issues and your skills first hand. The leading and feet handling issues are easy enough to fix, and spending undemanding time with him (A LOT OF IT) will help his issues toward people, but him not being handled by people much is where it concerns me. You might possibly be taking on a close-to-wild animal. You have to go about things so much more carefully with a horse like that. A lady down the road from me wants me to help her with her nine month old filly who has never been haltered before and has never had her feet trimmed (luckily she has worn them down on her own to where they aren't horrid, but still). She's pretty scared of people, a big introvert, so she will be challenging, but I look forward to helping this little filly out.
Would there be any way for you to take him on a trial period? That way you could work with him and see if he would be too much for you?