HELP!!! MOTOR HELP ID NEEDED

[Old car Buff]

Ok Fellas...This is the second time this ole guy is tryin this. I made a post and added a picture and it was evidently too big and when I hit your back button everything was gone! Im a Mopar fella myself but Ive owned everything from Fords to a Desoto and love em all!
My queston is that I have come across what appears to be possibly a desirable piece. I dont have the knowledge of all this numbers matching thing, nor the money.... I got me a wife instead! Ya all be sure to get you at least ONE of THEM to keep you from getting what ya really want in life... Ok enuff said by this ole guy!
I have a 512 Casting block with what appears to be some sort of VIN number on it. Eyein it all up I figure its been decked but there is another number up over by the oil filter. Thats lookin like # 19N647907. Bought the whole shabang in a 55 Chevy old style gasser that I jus love. Wonderin what I got me here for a motor. Any help you younger fellas could give me would be greatly appreciated.... and guys? Could ya have me up a Rebel Flag down there with the smileys when I come back?
Thanks again for any help you can give me. If someone can even steer me to the right site to ask if no one here is certain I would be grateful. Thanks again Fellas.