Today, dollar for dollar, is the 318 faster than the 340 ???

If there is one thing for sure, you should be able to get the 318 up and running before the 340 on a cost basis of cheaper (since your saving a lot of money by not getting a unknown quality 340 block) and very well possible quicker since many already have the 318 to start with.

I have not yet had a 273. I have and had all the others stock displacement sizes. Just for fun and only for fun, I’d thought I’d waste some money and build a 318 just for @AustinGriggs 318 fest he has every year.