I have a '74 Charger with a 400 engine and i want to put a 440 in it.  What kind of problems am I going to run into.   

There should not be a problem as every thing is the same, the only thing is if you are running an auto trans the kick down linkage might need to be replaced with one from a RB engine but Im not sure of that. 

The 440 has a higher deck height than a 400 does (block is taller).  This will present a few issues such as header fitment, belt length, and accelerator cable set up (depending on which intake you choose).  All the parts you need are available in the aftermarket, and/or can be adjusted if you are creative.  Obviously you will want to make sure your accelerator pedal is not binding prior to operation.  Have fun  

got the new 440 in with hooker headers and 3in dual exhaust with super 40 mufflers one problem the hole for my dipstick is too close to my engine mount for my dipstick tupe anyone got any ideas  

keep the 400,its a better engine, thicker mains and shorter stroke,Ill buy the 400 block if the last 3 digits on casting number is 630,im located in s fla and can build a 550 hp stock stroke hyd cammed 400 on the cheap, 400 mains are thicker than a 440, 440s for the most part are garbage due to the tall deck height and over 650 hp snap goes the crank and or webbing surrounding crank,if your 400s standard bore let me know, Ill take it off your hands, 530 also do ,if your interested email me at mopar 1962@comcast,net  

I'm new to the forum and not sure how to send a private message so I was wondering if you'd be willing to tell me exactly what you do to a 400 that would make 550hp.  I'm rebuilding mine now and want to give it some more power.  Thanks.  

400, easy, install a factory 440 steel crank. This will get you to 452 cubic inchs.
Then install the mopar performance 509 hydraulic cam, or the .528 solid mopar cam. Holley 850 double pumper with annual discharge nozels, big tube headers, 10/1 compression, 452 heads ported and polished with big valves.  
Edelbrock Performer or Torker intake.
 This set up will run 11's in a B/body. I personally built a 440 with this combo which made 540 h.p.
The 400 with the 440 crank should make more due to the lighter internal parts.  

Does the block need clearance work to run a 440 crank or should it fit fine?  What octane gas will I need with 10/1 compression?  Can I run dual quad carbs(dual 500 or 600s?) instead of an 850 holley, or is it better to stick with the one?  Thanks.  

I've built 3 451's.  The last one needing counterweight to block clearancing.  The firstone needed counterweight to piston clearanceing (short rod, KB pistons).  Just depends on block and crank years of manufacturer.  My first 451 was 10:1 with a .585 Comp Cam and ran 10.80's to 11.00's in a 3350lb car with 9 inch converter and 4:56 gear, and an 850 Holley.  I found the Holley 830 with annular boosters to be quicker then the 850 though.  

Better atomization.