The correct way, you most likely should I guess, on the 89 Firebird 2.8v6 was gutless always even when my mother had it new from Pontiac and then at 50k was even worse, but the inline worked fine as it does on the 300zx, I only had the firebird for like 3 months after we installed the inline on it so around 3200 miles on it, my 300zx has been on it since 2000 and was around 121k then and is almost to 190k now and seems to be ok, never noticed any loss of power after we installed the inline ran as strong as they did before the intake ones went bad or got bad.
I love GM auto, they have always been one of my weakness in auto, but they really should have been more creative like the import people was and made a cover in the trunk or under the rear seat to change the fuel pump. When the firebird went bad everyone wanted like 700.00 because the fact ití* a rear wheel drive car and the tank has to come off the car so this means removing the rear axel on the older ones and unbolting the transmission and such or either risking it as a few places told me they had done and cut a hole above the fuel tank (inside the trunk and remove and replace that way) they showed me pictures and looked ok after they had installed a door, but they wasnít responsible if they might punch the tank or blow the car up or for body flex afterwards so I passed and we installed a inline on it. The 300zx was an odd ball, as the way the tanks mounted in it you have to drop the tank also (was like what of course it was around the same as the firebird but the pump was higher of course so it made it like a 1200 job, so in went the inline pump!)
I am going to call a few places and see what the cost will be to have the intank one done, if its over 150 in labor, I will go the inline route as I know how much the fuel pump cost and thatí* too much money as far as I look at to replace the pump.