One of the attractive things about the 7M is the wads of low down torque - you'll lose some of that with the shorter stroke and drop in capacity.
i actualy fiddled with a few engine parameters once on a desktop dyno... you lose the torque, and you do gain considerable revs. but with that, the power and torque bands go up... BUT strangely, despite revving more, the lower capacity and shorter stroke NEVER managed to regain the absolute torque and power figures of the original 7m setup.
pity the 7m just doesnt rev little better - hen it would be an absolute screemer... gues tht why they changed the bore and rod legth and created the 2jz...