327's are great motors , and they like to rev . They were small main bearings prior to 1968 , and then they had larger main bearings the same size as the 350 for 68 and 69 .
It will physically bolt into the Impala/Caprice using the engine side mounts from your car .
Make sure you use the right flexplate for your starter , they come in 153 tooth ( starter bolts right across from each other ) and 168 tooth ( starter bolts staggered ) , and that it has the right bolt pattern for your torque converter . Can more than likely use the one off the 305 .
Use a cam intended for the gears and weight of your car , its all to easy to overcam the motor and then the cars performance is lacking .
It may not be emmissions legal if they check the block numbers in your state , even though once all the stuff from your motor is on it , it would look like your old 305 . If they don't look , or don't care , then your good . A rebuilt motor in good tune with your 305 stuff on it could burn cleaner than your worn out 305 did .