If you build a any cubic inch small block with the same parts and quality, the horse power will be very close. this big difference will be in the torque. if you don't beleive that, buy desktop dyno and build a vitual motor. you will see that if only the cubes change, the torque will change but hp will stay close.
the other reason people like the 327 is hp now. they wind up quicker. if someone here really wants a 327 let me know. i may still have access to a steel crank for a large journal 327.
do your homework and dont get the early 327. small jouranl bolts are scary to look at.
best bet for a non-gearheaded motor swap...... edelbrock complete crate motor.....quality.....complete....no messing around.
jake