You may need to remove a small amount of metal (maybe 1/4") in the windage tray where the oil pickup goes through just to give enough room to wiggle it into place. You will also want to throroughly clean the chassis rails and surrounding area so that you don't knock a load of gunk and crap into the pan whilst jiggling it up there. I would also stick the gaskets on the block with RTV first.
It's not easy nor plainly evident whilst lying on your back, but it can be done.
God luck,
Julian
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