Stroking a 340 in a 68 Dart GT

Read around 30-35 threads and whole bunch of thread titles couldnt find answer to my question so hopefully this isnt a repost.

Have a 68 340 block, and some will call it blasphemy to take out the stock forged crank. I want to throw in a 4 in stoker crank would it be possible to only change out the crank and keep rods+pistons in by using a higher cc head and bigger gasket, or swap crank and dish pistons, or would i have to do the whole rotating assembly, Only aiming for around 400-450 hp and torque. in a 68 Dart GT

Crank will be for sale once i make the swap for anyone interested, also have Race demon 850 carb with 340 victor intake if someone wants anything, make offers.

Respectfully,
Nate Thompson