Advice on small block (and transmission) shopping?

Hey, guys!
some quick background-

I have bounced on and off this forum for a few years now...not being sure what I wanted to do with my '73 Dart sport. The car was my pride and joy when I was 18 (back in the 90's) and I was never able to let it go, even after it was parked as I moved on to sports cars and Mustangs.

Well...as much as I love my 2011 Mustang GT, the Dart is still my car and selling it would probably kill me. I'm getting serious about getting it back on the road in time for the spring and possibly ditching the blue oval.

The body is in good shape, interior is still clean (minus a tear in the driver's seat)...but the 318 has had it.

So I'm looking for a fresh(er) small block. Currently the car has a tired 904 (slipping, probably needs a rebuild) and the 7.25" axle/open with 2.73 gears

So as I start the part search, I'm hoping for some advice on picking a donor motor....years, versions, etc. for a relatively tight budget.

I'd like to drop in a motor that will have a broader power band than the 318 (though I did love that motor), reliable...but still have room for performance mods down the road...so something with stout internals.

Is there an optimal version of the "Magnum" motor that is the strongest?

Secondly, would I be better off having the 904 rebuilt with stronger components or finding a 727?

Third, my rear axle assembly search has been frustrating...I will certainly replace this down the road (probably with a custom axle since A-Body 8.75" assemblies with the larger 4.5" bolt pattern are all but impossible to find around here)....but in the mean time, how much power will the little axle withstand, assuming I don't abuse it?

Thanks for any input, guys. I'm starting over from scratch!

By the way, I abandoned the idea of buying a junk yard 5.7L Hemi (can be readily found for ~$2k) since the consensus is that the extra work doesn't justify any performance edge (do you guys agree?)... which is unfortunate since even a stock 5.7 puts ourtat least 340hp and supposedly bolts up to a 904...

Mike

Here is the short answer:

Keep the 904 and rebuild it. Can be worth 1-3 tenths in the 1/4 mile (depending on who you talk to).
Get a mild 360 and rebuild it, or put a 4 inch crank in your 318.
Ditch the 7.25 rear and upgrade to something else (8 3/4, dana, 9 inch, etc)....for what its worth, my best friend broke a 7.25 rear with a nearly stock rebuilt 318 on the first trip out of the driveway.

You will get 8 gazillion different opinions on what's best, the best thing to do is first determine what you are going to be doing most with the vehicle and then plan according to that goal while keeping your budget in mind. Take the time to research all the suggestions and then make your parts choices.

Here's what running in a 64 Dart used primarily as a daily driver that has some decent power and attitude:

'77 360 LA motor, stock bottom end, stock heads with EGR ports tapped and plugged
Holley Street Dominator intake
Lunati cam 288 adv duration (233@.050 I&E) .480" lift
1.6 roller rockers
Holley 4777 650 cfm double-pumper carb
Shorty headers with 2.5" dual pipes and flow master 40-series mufflers
Rebuilt A999 (heavy duty 904) auto with shift kit and 2200stall converter
A-body 8 3/4 with 2.93 open gear (good highway gear!!)

This is a fun driver that sounds great and with the taller gear cruises on the highway at 65 all day at roughly 2600 rpm. Motor combo dyno-ed at approximately 325hp at the crank so it's not a full on strip killer but plenty enough power to have fun in stoplight action on the street.

Here is another opinion/option;

A Magnim 360 from the J-yard
A B&M flex plate is needed for a external balance Magnum to a neutral balance converter
Rebuild the 904 stoutly.
A cheaper way out for the rear is a 8/1-4. They normaly come with the bigger bolt pattern. They will hold plus 450 HP. Though I recommend new innards (sure grip) for more than 400 HP.
Swap out the roller cam for a roller cam more suited for the build and add a intake, carb and headers if so desired.

MP's old create motor was a stock Magnum with a single plane M-1, a MP roller cam, headers and a 750 Holley that always dyno'd north of 400 HP.

My advise to you is to do what you can afford, but keep all the original pieces if they are from that car. Seems silly but someday you might want to put the car all back to original and you cannot get any more original than the pieces that came from that car. I wish I had kept some origianl pieces from different cars because once they are gone there is no getting them back!! Just my two cents worth!