I bought my first classic car '69 bird ~5 months ago for ~$30k. It was suppose to be turnkey but been running into issues ever since purchase. Took it to a classic car restoration where they did a tune up, new master cylinder, and a few other things which cost me ~$3k. I've had it for about 2 months since the tune up but it's been knocking. I called them and told them the knocking sounds like a new issue but they said they didn't notice anything and just keep an eye on it if it gets worse. I've been driving it since and it broke down on me today. Was driving when heard a loud pop, car shut off, and I coasted into a parking lot. I looked underneath and oil was pouring out.

What are my options now? or if any suggestions on next steps would be great. Engine WAS a "rebuilt" 400. But I don't want to put way more money into it without its value appreciating. I'm looking at some of the '69s currently for sale and wish I had reconsidered this purchase.

Thanks in advance for any suggestions or things to consider!