You need the 302563 diaphragm for that tank (3 on ebay for $10 including shipping), I’ve used Fel-pro 3018 Cork Rubber Gasket Material for the tank gasket, and these hard fiber washers for the screws from McMaster Carr (if they’re the screws that use washers and not o-rings).
Also if you go this route here are a few words quoting Frank R. from a post a few years back:
“I use sealant (OMC Gasket Sealant) on both sides of the cork [tank gasket]. Screws, depends on which type it has. O-ring type, replace the o-rings, otherwise the washers type don’t really need anything but use sealant if they are in poor shape-or replace.
Diaphragm-no sealant needed. BUT if it is the metal push button type, the support discs have to be in good shape. Straighten them if bent in the center. I even go beyond flat a bit (the opposite of what tightening the nut does to them). If rusted around the center hole, either replace, or put the rusted one on the bottom if the other one is good (on top). Now for the push rod: The end right above the threads has to be in good shape and flat. If it is corroded/not flat, it will leak. Replace it. The knob: It is supposed to spin freely on the push rod. That is because if it won’t turn, when you push the button you have a tendency to rotate it, which unscrews the nut off the bottom-and it will leak. Finally, yes a drop of sealant (847 or Permatex aviation) on the threaded end and lockwasher, and flat end previously mentioned to keep fuel from going up through the hole.”
