1970 Dodge Dart 318 upgrades

OP, this may sound like a sily questioh, but you'd be surprised how differently engine builds can go, depending on the end goals. What are your goals and planned uses for the car and engine over the long term? If you are on a budget, then that long term goal should be front and center so that you don't waste $$ going down the wrong road, IMHO.
And what work is bring planned in your rebuild? The point about higher compression pistons is on the table in a rebuild, and is a step forward for your 318... its weakest attribute is low compression.