Anyone here put a 354 in a Dart?

The 354 block is very close in all dimensions to an LA.
Motor mount ears, and trans bolt pattern are the same (spacer is needed because of longer crank flange on the Hemi)
Exhaust is actually easier for the Hemi than for either BB or SB Wedge, because the Hemi has downward facing exhaust ports.
Swap would be much easier than you think

Couple of things are not quite correct here. The bellhousing pattern is the same, but the dowels are located differently. Also, the moutor mount ears are not the same as the LA. The driver's side of the block requires one corner of the 318 mount bracket to be relocated. No biggie. Takes like 15 minutes with an angle grinder and welder, but they are different.