downsides compared to the chev7 4.3 would be it would need oil mods to the timming cover and the hole to the pickup in the block(not needed buy always good to do)..both easy to correct..buick is detuned from the factory too, rv or mid range cam would be a nice upgrade, along with powertimming the distrubutor, both easy and cheap. engine runs a tad hott compared to the chevy but all buicks run on the hotterside..
pros would be lighter engine (375 vs 450), distro up front, more torque once you power time it

looking up the fireing order now