The 340 is the biggest POS V8 Chrysler ever made.

I ran a program where we had a 340 bore but a 2.96 (about) stroke and a longer rod
you have to spin them much harder than a 4 " stroke 4" bore to get the same amount of air through them
you get a little more hp with the big motor but not much but a lot more down low I'd build a 4x4 everytime unless there were rules not to and even then...
you do have to do all the oiling mods to make a high rpm mopar- or anything live
same also with the AMC with it's Buick style oil pump
The amc was supposed to run a stock plus a little 360 4.060 AMC bore in Trans AM so more bore and less stroke than the Mopar- same with the Pontiac
on the AMC we used a 4.1875 bore slightly over the 4.165 401 block which AMC cast with 4 bolt mains , filled in bulkheads thick deck and 360 on the side- really short stroke when legal
was 4.250 x 3.750 (sound familiar) giving 426 NASCAR at Riverside The big bore AMC out breathed everything except the BOSS ford but had a better torque curve and better out of the corner than the Mustang basically a better head than the Chevy, Pontiac, LA (not W2) A Wally Booth head would outflow any of them but hard to keep together and definitely not for anything but drag racing
Similar but earlier 390 block was run by Hayden Proffit in the blown fuel Grant Piston Ring FunnyCar- what was learned in that program came the 70 Dog leg heads and better blocks
racing works!
and you have to fix the oiling- even on big blocK mopar