Google 7mm Mashburn. It's a round that's been around for quite a while and was originally made from shortened 300 H&H cases. Now everybody makes them from 300 win mag cases because it's just a simple neck down to 7mm. It is for all practical purposes a 7mm-300 win mag, your friend's cartridge will be basically identical to it.
That's where I'd start for load data. From what I've read you can expect about 150 fps more than a comparable 7mm rem mag, usually about 3200-3250 with a 160 gr. bullet. It's about halfway between a 7mm rem mag and a 7mm STW.