If you can get him into the 200-220ish apft range, his time in basic will take care of the rest, and he'll be in a good spot. My first one was about a 210, and my final one was a 285 before I left Benning.
We would usually have an hour or so of time each night we were left alone in the barracks. My buddy guilted me into doing pushup/situp routines routines with him for like 20-30 mins each night, and that helped so much.
This may be restating the obvious, since you've already been there, done that, but.. food for thought:
If he doesn't already, get him setup with a larger national bank checking account that isn't going to rake him over the coals in monthly fees, direct deposit, or debit fees. Send him with that account number & routing number, plus the card. At benning, if you didn't show up with an account, or didn't know, they set you up with a local shitty bank that was really expensive, with monthly fees and stupid debit fees. Plus it's a pain in the ass to switch over and close that old account later, (especially as a new PVT) so it's better to keep the same one throughout. I used BofA, and it's been good so far.
Along the same line, make sure he has at least $1000 in that account before he leaves. I don't know if he works, or if you want to work out a loan, or just give it to him. He's going to have an opportunity to spend a little money to make life a little more comfortable. One of the civ people fucked up typing in my routing number, and I didn't end up getting paid until about week 9. It was a clusterfuck to get that fixed. I went in at 24, so I had more than enough in savings to float that, but $1k is good "just in case" money.