The cam specs can't be that different, but the same cam in a smaller engine is going to make peak power at a higher rpm than a larger engine. There is really no point in wringing a 5.4 over 5,200 rpm with a stock cam. They simply aren't going to make any more power at a higher rpm. If you want higher rpm, you're going to have to get a more aggressive cam profile. I just don't see the point of putting better rods in a rebuild if you're not going to put forged pistons in it too. If it were me, I'd get the MMR shortblock and have someone local freshen the valves and replace the valve springs and use new VCT hardware when I reassembled. It would be a great time to change the cams, but these are not low budget items.