I might have gone into overkill for a street car, but I have a 496 to put in mine. Just remember, if cost is an issue, that the more HP you build, the more $$$ it's gonna take.
Adding up the stroker with worked Eddys, lightweight aftermarket internals, MSD box & distributor, etc. I think I've got close to $9K in it, then, of course, the cooling has to be upgraded, then the transmission, better beef up the rear end and put Moser axles in it... hmm... better have a torque strap... then it needs a scoop because the motor won't fit, different t-bars, better brakes, then I got thinking... the Schumaker tri-y headers were smallish for all those cubes... so I got a set of Pro-Parts, then had to cut the fenderwells a little, and modify the headers and get them coated... so now the 2-1/2" exhaust is gone in favor of a 3" setup... All this stuff is done now, just waiting on a little paint work before the motor goes in...but now I'll probably need a roll cage in it if I wanna take it to the strip...things can get out of control, especially if you don't have a ton of money to pour into it all at one time.
It'd be tempting to do a stock rebuild on your 440 and just drop it into your Dart. On the other hand, you could sell the 440/727, put a shift kit and converter in the trans, and there's usually some sweet deals on 340 motors on different Mopar sites. A guy listed one with Eddy heads and new cam, roller rockers, etc. for $2,000 on Moparts a few days ago, and it comes with E-body coated headers that you could sell to get some for an A-body. There's another 340 on there right now that has EVERYTHING, right down to the MSD, plug wires, carb, etc., for $1,800. That's some cheap fun, right there!
It all depends on how crazy you want to get with it. There are a TON of fast small-block A-bodies out there... I had my engine pretty much built when I bought the car, and it was already set up for a big-block.
If I were in your shoes with a 318 car sitting there...I'd probably scoop up a 340 or something and just jam it in there. You could be doing burnouts in a couple weeks!