1974 Duster 340 Engine and 727 Transmission Questions!!!

Here I go with my 1st post...

I have the following a 1974 Plymouth Duster with a 318 engine and 904 Transmission.
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The 904 Transmission measures around 31 1/2 inches long.

I purchased a 1973 340 Engine, 2780930-340-7. Engine # 3B392420. Date 02-08-73.
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I also purchased a 727 Transmission that measure 25 inches from the top of the case to the bottom where the silver ends, PK4028406 5423 2135.
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Is this set up going to work or do I need to find a different 727 Transmission that's longer?

Also found another 727 Transmission PK322277 4546 9495 that came out of a motorhome. Will this work with the 340 Engine?
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Or should I stick with the 904 Transmission that in the car right now and connect it to the 340 engine? Everyone is telling me to go with the 727 Transmission. Ok but with one?

So confused with these 727 Transmissions!

Keep in mind, both 340 Engine and 727 Transmission are both being broken down and completely rebuilt with all new parts. Just wanna know I have the right 727 Transmission BEFORE I start all the work. Let me know. Thanks...

Alec!!!