340 or 440

Hi there OP
I have a lot of experience with BBM and SBM going back to the late 50's
Do the 340
Doing a smogger 440 is no advantage power or weight, just some torque
too many changes have to be done to a late 440 to make it "better" than a SBM
Now if you had an early Magnum or 6 pack it would be a different answer
Late 400s and 440s make more heat than power
you need pistons and most likely balance
therefore a stroker kit makes sense
If you are not going that way do the 340
If you want to build a 440 do it later
stock sucks