Fuel pump

[Feelstranger]

O collectively wise collective...
I need a new fuel pump.  I have a new pump that was never installed in a previously owned 88 5000 QTA.   I just pulled the pump from my 20V and it is a Bosch 63 mm unit (original?)  So, would the unit I bought for the 5000 work, or are they likely to have different pressure or flow rates?  Otherwise they are the same in size and shape.
Is it possible that this could be fixed without spending any (more) money???
Thanks
Nat