You will have to be very careful with your cooling situation on these motors.
If you have the blocked bored especially. The 2 center cylinders are sistered together(share the same center cylinder wall), any boring and little too much heat will crack out the center cyl. wall...then you'll end up with a 400ci anchor.
Some people love these motors, personally I wouldn't have one shoved up my ***** if I had enough room for a whole truckload.
I would probably save my cash and go with either a stroker motor or step up to a Bigblock. Also your parts availability is limited to pretty much this motor only.
Like I said that is just me though...