My 273 turned out to be a 318...what did I buy?

Hey there. I bought a 1965 Valiant a month ago. Seller said it had a 273. Finally had a chance to truly get underneath it and look at the engine block casting....4387530-31823.....a 318! Look at the passenger side....08-87...from 1987! This is my first mopar and I am getting into cars a little later in life. I don't have any friends who are really into older cars so I am reaching out to my new community. Here are a few photos of the engine....What do you folks see? The good, the bad, the ugly....I'll take all feedback. I thank everyone in advance for their help!

Steve

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Not a bad thing. 87 is probably a roller cam engine with the famous 302 casting heads. Good chance of it unless it's been messed with. A 318 4 barrel with headers is a swap that many 273 guys strive for.