Using 2 alternators .....

MSD only draws what it needs, typically 1A per 1000 RPM, so another alternator wont provide it any more power as 1 will usually work just fine. Many hi watt car stereo installs use multiple alternator installs. You could mount the alternator low to offset the PS pump location. Im not sure 2 regulators are needed. The parasitic loss on an extra alternator is gonna be minimal as they are both gonna be running equally under rated at ~50%.