I would make an offer but shipping an engine even a short distance would be too expensive.

My advice would be to learn to love Ebay. Anything you need will show up eventually. I have found that most people who sell old car parts are honest. But you have to ask questions to be sure they haven't omitted important facts about the condition of the parts. The seller may think he's selling a good part till you tell him what to check. For example brake drums may be turned beyond the maximum diameter and look like new.

ALWAYS check the sellers feedback first. If they have a lot of negative feedback from dissatisfied buyers don't bid. Don't even email them because they can't be trusted.

I have 129 positives and one negative from a guy who didn't pay. check the feedback of the people who gave the negative feedback as they may be a real jerk who always have problems. I had two bidders with -2 feedback who didn't pay. when I gave them a negative their accounts were terminated before they could retaliate.

If they have 0 feedback or a low number an email isn't always enough. Ask for their phone number and talk to them on the phone to determine if they are genuine or full of crap.

If you buy an engine or parts car it should be close enough to San Diego so you can go look at it before you bid. If the seller doesn't want you to come see it don't bid.

If the seller wants you to send the money by Western Union it's probably a scam. If you send money by Western Union to a guy in Texas it doesn't mean that a guy in Texas will pick up the money. Anyone with a fake ID can pick up the money anywhere in the world. A postal money order is best because if they don't send the goods it's mail fraud and that's a federal offense.
There's a lot more crooks on Ebay than ever and they keep coming up with new scams so you can't be too careful. But like I said used car parts isn't a good place for scammers to make money.