Welcome from PA - nice car!
You talk about eventually getting a bigger engine. That's fine, and many have transplanted a big block into their cars. But, doing this means new motor mounts, new brackets for alternator, A/C (if present), power steering, etc. You will also need a new transmission, maybe linkage, etc. You probably need to change the torsion bars as well. The bottom line is there is a LOT of stuff to change if you change from a small block to a big block.
However, don't overlook the power and benefits of a small block. A small block weighs less and will help the car's handling. All the accessories you have will continue to fit. I have a big block 70 Road Runner and a small block 73 Road Runner. In the 73, I just built the 340 into a 416 cubic inch stroker. I am still just breaking it in, but man it runs STRONG! I am super pleased with it. So bottom line is if you eventually work to improve the power of your car, please be sure to consider a stroker small block.
Regardless of all that, best of luck with your car - it looks great!