The fuel pumps have 1 way valves in them. If you just put an electric pump before the mechanical pump, it will push fuel to the carb no problem and you can leave it all well enough alone. Then again... If you don't want it to look that ugly under the hood a block off plate will fix that right up...

If it were me, I'd install the electric pump in line with the system just to prove to myself that there was a fuel delivery issue before I removed the mechanical pump.

91 YJ
2 Seater Sand Rail
Handfull of other fun toys...
And a brand new, spit shined, B.S.
Oh, and a job to boot.