Big blocks (generally) require LESS maintainence than a built up small block, under the same use, especially if the horsepower is equal, since the BB does not have the strain produced by the Hi-Po cam, compression, etc.....which is required to make a SB perform to the same level as the (equal horsepower) BB
No replacement for displacement is a fact. As to handling, especially ease of slow speed steering, I do hear the small block or an aluminum BB may be better since these cars generally do not have power assist steering. My turnkey West Coast cobra (slated for April 2002 delivery) will have the monster 514 CI Ford bracket race motor, with Holley electronic fuel injection (throttle body, looks sort of similar to a carb)
http://www.westechperformance.com/pa...s/514ford.html
The West Coast cars have 4 wheel power ABS brakes, and power assist steering, and are balanced and designed for the heavy BB motors, they also weigh more, (have a heavy space frame and slightly larger body) and so they need the extra power to stay competitive with the slightly lighter (sort of) original designed replicas like SPF or FFR, ERA, etc..
Your lighter SPF would wail with either of the motors you mentioned. If you want a manual tranny, consider the 6 speed R.O.D. tranny I am having installed in mine, it is about $2800 new, retail. (Richmond Over Drive)