The later pumps push higher volume and pressure.  Some say it gives a better throttle response.

this is only my opinion. if you put in a higher pressure pump, the pressure regulator would regulate where it should be and the computer, injectors,etc control the volume of gas that the engine needs to run at the proper mixture, so i don't see any advantage of it. the only way i could see it  benefiting anything was if you were having other mods done that those changes would be needed. again, this is just my opinion.

 I had an 84 for nine years and  the first thing I did was put the 85 Fuelpump IT DOES amke a difference. It maintains the pressure Better than the stock one. There is no regulater on the T B s they are sealed. They CAn be regulated if you  have the tool to get inside. You need to drill a hole in the bottom. I DID NOT do this there is a website Crossfireinjection .com. Get on it for more upgrades. My 84 was putting out about 250 H P with minor upgrades. Accell ignition,bosh Plat. plugs Exhaust eliminator Forced Air  inductio with a K&N filter .Also a A D S chip nolonger available T C I shiftkit Worked for me  Go to site it will show you how to do the forced air by cutting a hole in plastic just infront of the Radiator to MATCH the hole in the Hood. G M did that to keep H P down in 84

good point wingnut. forgot about the TBs on the 84.