It is a similar swap to the 2.4l swap. The short block can be had for $1700 new from Dodge. Our stock tranny bolts up. You will need to focus on working out how to make your crank angle sensor work, which will probably mean a new timing wheel needs to be made as the signal and tooth count are different on the A853 from the 420A. If you go standalone, this will not be a problem. There are few other revisions you would need to make, but those are minor in relation to getting the crank trigger sorted.

05 Mazda RX-8
06 Lotus Elise