I just installed a new Melling High volume pump in mine, you have to check clearances with the oil pan, first off you wanna make sure the pickup isn't touching the bottom of the pan, and the pickup tube isnt contacting the side of the oilpan, if it is, very carefully bend it untill you gain clearances. Next, I had a clearance issue between the top outside edge of the oil pump and the oil pan, I just took a ball peen hammer and made a slight indent where it was making contact. It may have been ok with the gasket, as I checked all my clearances without a gasket in place, and It really only needed about 3/16" of clearancing. If you have any other questions lemme know.
HTH
Josh