70 mustang 351W build.

Here is how to ID the transmission in the car.
http://www.fordification.com/tech/transID-auto.htm
Machine work, and parts, plus buying speed parts can get very expensive. Speed costs money, how fast do you want to go? In order to use roller rocker arms, you will need to either buy heads that are drilled for an adjustable valve train, or get yours done. Machine work will add up, but can be managed. Shop your local Craigslist for a lot of these parts. KNOW what you are looking for, and what you are looking at! A basic rebuild on a 351 can be done for around 1500 dollars in new parts, plus machine work. Summit racing has complete engine kits that include pistons, rings, bearings and gaskets for around 450 dollars. You will need a cam kit, and ignition, exhaust, etc...Lots of this won't change. What ever you build will require similar expense. By sticking with the block that came with the car, you will minimize fabrication costs, and be able to use off the shelf items.
http://www.summitracing.com/parts/fem-mhp176-311/overview/make/ford
http://www.summitracing.com/parts/cca-k35-242-3/overview/make/ford
See if this guy will sell the intake and carb by itself:
http://chattanooga.craigslist.org/pts/3536080643.html
You can buy a duraspark distributor and module for cheap at the local junk yard or new at the parts store.
Roller rockers?
http://chattanooga.craigslist.org/pts/3669455714.html
Plus headers, mufflers, rear gears to match cam, plus torque converter. And then don't forget normal stuff, like a new heater core, carpet, plugs and wires, etc....
When I went to auto tech school, they only let me work on my car only during "shop" time, and about an hour and a half, after class.

I was merely giving you some options for the build. I didn't know if the engine was running in the car now, or not. Is it a 2V engine? 4V? What do you think it is missing, that is keeping it from running now? It's way easier to stay motivated about a car that does run, rather than a big paper weight in the yard..

2V or 4V, refers to the Venturi's. Did it have a 2 barrel or 4 barrel intake? I doubt that it got ruined over night, however, you will want to drain it now as soon as you can...