A 340 is a short stroke but it's not really a small motor

The issue with the 340 (in todays way of thinking) is the piston is HEAVY and the real way to take advantage of the short stroke is to lighten the piston and use a longer rod.

I grew up in a time (late 70's) when I personally remember pulling out 440 RB's out of B bodies and dropping in 340 W2's with Isky solids and the cars going faster. Back when high 11's was a respectably quick street car...and the car you drove to work every morning. 4.30's and 4.56 went in at the same time, not much fun for those guys cruising the GSP or NJT at 3800 rpm...but they were winning.

I'd try to use a 2.100 or 2.00" SBC journal rod and a 6.25" 6.30 rod, if you want to keep it stock stroke the piston CH will only move up <.200 but it will help the weight by also using the lighter SBC pin. Some guys are using .812 SBF pins too. To keep it streetable in terms of grunt probably a 255-ish @.050 solid fairly wide 111-113 and in around 107, with a 285-ish CFM head and good valvetrain you should make 500+ at about 6400 or so at a streetable 11-ish CR....plus have decent (but not great) bottom end torque. If it were me I'd offset grind it to 3.45-ish and get the slug that much lighter and pick up a few more cubes....or (cheaper) just do a 360.

my old W2 340 dart 4 speed went high 11.80's 33 some years ago on street tires hazing in 1st and second....back in 1980. it was steetable, V gate and all. Fun times.

340's with a stick are still one of the most fun combos I've ever driven, I loved beating cars sporting 60-100 more cubes. Of course I never tipped my hand I was sportin' the W-2's...would you?