Uncle Benson showed me along time ago how to make a gasket, gosh it's easy, The proper material for one, then take a ball pein hammer and tap around the area to be duplicated, remember to just tap tho, the holes are acomplished by the rounded end of the ball pien hammer, locate the hole by pushing the hammer into it, then just a tap or 2 and you have a hole, on aluminum you have to tap lightly but you can do it, just take your time, then a film of blue or black silicone and it shouldn't leak at all, but I would much rather use the proper gasket.
dave