1978 Porsche 928

Bro,

It's a 1978 porsche 928 "in decent shape" with no engine and with torn seats, selling at $750, with clean title. Isn't this a good opportunity?

Then there is this engine: https://ebay.io/m/ixVEhc for $2,200:

But then there is this engine for $4,500 so I'm not sure the appropriate price: https://ebay.io/m/hhkmAz

Can you estimate the cost of putting an engine in? Would you say it's a good idea, or does this look like a waste of time and money?

Piousbox