Need Advice on Low(er) Budget Race Build
First of all, if you are going with a 66 a-body a 440 will be a nightmare to intstall and work on. And unless you're going to go with a $10K back-half and big rubber, it's very impratical to say the least. AND very nose heavy.
You can do a stock 318 and 3.23 open gears and maybe get in the 14's. You can do a warmed up MILD 360 and a 3.91 sure grip and get it into the 12's pretty easy at that weight.
I can tell you from MANY years of experience, it's much more fun to get the car "done" at a given stage and go play with it. You can always upgrade/go faster as your time and money allow. Many projects have been "planned" and the owner gets in over his head (either mechanically or financially) and loses interest.
If I were starting with nothing but a stock 66 Valiant (cool car, by the way!) I'd tie the frames, add an 8 3/4 with a 3.91 sure grip (or mini-spool for cheap) build a pump gas friendly 360/904 with a 10-11" converter, decent hydraulic cam, air gap intake, 750 Holley and have a deadly consistant bracket car that would be very streetable, even with the 8x26 tires you're going to be limited to. The fuel and ignition system can be very basic and still accomolish this goal. If you have $2000 in your hand and the car doesn't need alot of body work, that will almost do a complete rolling car (if you shop wisely) and be ready for a motor. But I would focus on the car first; it doesn't do any good to spend that first chunk of dough on motor stuff and have no where to put it.
I'm currently doing a 69 Dart street/stripper on the cheap. It will have a 408/904/8 3/4 and I fully expect to be in the mid 11's in street trim for less than $6500 total. I could actually spend about the same and do a 440 and get real close to 10.90's, but I'm more into the small block thing lately...