If your 273 is a '64-'65 model, the intake will NOT bolt up to the 340. Besides the port mismatch, the intake bolt angle is different on the early 273 than on '66 and later smallblocks.
Since your 340 is a '71, that simplifies things quite a bit from my earlier post. The 273 torque convertor should bolt up with just the crank adapter bushing.
Did your 340 come with an intake or exhaust manifolds? The fit of the 340 exhaust manifolds is the same, early or late- as long as they are A BODY manifolds. Anything else is at your own risk. Just like the pic in my previous post, 340duster340 has early 340 manifolds fitted with the Borgeson box. Drop him a PM if you need particulars. MUCH better breathing than the 273 exhausts.
