Yes if you don't want to have hood sides, the 426 will work. If you want the hood sides, a 340 will work.
Please keep updating thread, Im interested in seeing what you do with the front suspension and steering. '33s are still tube axle and '34s are IFS one year only. You can easily Gasser(new Tube axle/vega box) it out. Its more challenging keeping the stock suspension, adding disc or keeping drums, and using the existing steering or some form of. Just keep updating as it helps everyone else building these cars. working on a '33 Plymouth sedan myself, 318poly/TF/tricarb/8.75 rear with the tube axle.
https://www.flickr.com/photos/walt_felix/3630026382/in/pool-hemihotrod https://www.flickr.com/photos/spike428/4692685808/in/pool-hemihotrod
I personally am keeping my flat head 6 and am going to pump it up with dual carb, headders, cam, bore .60, and then gear the rear end with a swap. otherwise my car will be MOPAR 100%, no other motor should be used in a dodge, same goes for chevy, I hate seeing a Ford car with a Chevy engine, why didnt you buy a chevy, I have only seen a few chevy cars with a ford motor and those dudes were ghay. I do see mopar with both ford and dodge but that makes no sense to me as Dodge made ford parts before they were Dodge which PROVES superiority. p.s. see pictures of engines with different types all in dodge 33 / 34 cars.
There is something to be said for using a Mopar engine in the Mopar cars. Part of hot rodding is thinking outside the square and belly button engines are a easy way out. I take my hat off to those who use Mopar engines. Dare to be different and reap the benefits. Sure chev sb are good engines but why follow blindly?
As long as we are talking about interchangeability of grills - I have a question . Will the rear fenders from a 30 Dodge fit a '33 Dodge coupe ?