340 TA Value

I could purchase a short block from blueprint engines and sell my engine separately instead of building it.

Not necessarily Blueprint, but you said it right there. If the T/A does not exist any more, it is likely that someone in the know will be aware of the fact. If it is, someone would probably be very happy to reunite it. There are people who will pay you a good dollar for that engine. Granted there are some folks who would buy it to hold it for ransom. Regardless, you should be able to come out ahead overall.