Re: 58 evinrude fuel tank
Did a job today on 59 rude with single line system, may be of help to you. 1st problem, cannot rebuild pumps, so need p/n 388685 (Evinrude Johnson) assy includes mtg hdwe, but no gasket. list $47.60
Discard all old fuel system components that have been gaffed over the years, install new vac gasket at block and mount redesigned pump assy (uses same mtg location). route fuel lines and you are done. Test at WOT should push 2psi min. This one makes 2.7 psi.
If you have 2 line pressure tank system you can also convert, but you have much more work to do.
If you need inst respond to this forum & I will help you thru to "surgery" Good luck with the project.
Doug @ lakeside ranch