There really is an adapter on the block. It was a stamped steel affair. If someone had an oil filter on over tight, that adapter could have been bent getting the filter off. Remove the filter, and clean the area where it screws on. There is a big nut in the goo. Remove the nut, and there is a gasket between it and the block. Clean the part well, if it looks bent, it may be easier to buy one than to get it straight enough to seal. To get the proper gasket, buy an oil filter cartridge for a 54 Ford car or truck. It should have a fiber gasket. Check in the box before paying for it. The rubber gaskets will be forced out by oil pressure. Clean the area behind the adapter very well. All the crud here will end up in the main oil galley. If you cant find an adapter, seek John Mummert on Google. He carries new ones.