Hello everyone!
When I did my electric pump install, I used an OEM replacement pump from a '93 diesel van/truck placing a pre-filter between the tank and the new pump. I have an M1008 and the place right behind the cab, where the rubber lines from the tank meet the lines to the motor, I had to remove a small amount of the steel line to get the assembly to fit.( they do make small tubing cutters for close in work like that) The factory skid plate fit right back in place.
I would say at the very least remove, the old mechanical push rod, as mentioned, flexing the pump diaphragm without fuel to lube it WII eventually cause problems.
Another "short cut" I did was follow the front steel line forward, on my M1008. right below the fire wall on the frame is a brass block, it had the two used ports, one from the tank, the one to the original pump. it has a capped off 3rd outlet on the top side. I completely removed the old line to the original pump at the front of the motor, put the plug from the brass block in it and ran a new piece of steel line right up the fire wall to the filter intake, this keeps you from running to the front of the motor, up, then back.
Just a suggestion you might want to look into.
God luck!
Greg