swap out the slant 6

To answer your questions:

Is it worth it? Well no, it's not. The 318 poly is just a big engine and probably wouldn't fit in your car without some major cutting. It would be lot of work and probalby too much cash just to have something unique but not that impressive perf-wise. Basically there's a reson nobody has really done this.

I think it would be a lot simpler to look for a V-8 A-body, with some simple upgares like a four barrel carb and intake plus dual exhaust you'll have a great running car for a lot less money and aggrevation.

At 17 I know cars can be a lot of fun but you need to make sure your drivng record stays clean. One or two innocent incidents and you'll be paying a ton for insurance, for forever! Instead you should go to the closest track (might need to be 18 to race) and check out what it's like to run the 1/4 mile. You can shred some tires and be safe.