My 289 was vapor locking in hot weather due to thermal soakback after starting after sitting for a short time and a very knowledgeable friend that specializes in the original Thunderbirds ( my previous car) suggested an inexpensive Carquest pump back near the tank. I switch it on for startup when cold to fill the bowls and leave it on longer if the engine is hot. If it ever vaporlocks I can switch it on to clear it. Haven't had any problems since, so far.
The Carquest pump is an Airtex E8016S and is available many places for about $25.
https://www.ctci.org/gilsgarage/VaporLock.php