100%
I will say this though. Sure, you can build a sub-$3000 318. Guess what, if you have a 340 already or do like I did and search and search, looked on Moparts, looked on the nationwide Craigslist search engine, looked here, you can find a 340 block.
It might need a sleeve or be at its max bore after machining. But you can find them.
Point is, do what makes sense to you and if you have an LA build it. Who gives a **** what the bore size is. A better question to ponder is 3.31” stroke or a 3.58” stroke if you are on a tight budget.
Mental Masturbation! LOL!