I'd suggest the first step is assesment of the parts you have with the help of a good machine shop.

Get the block measured to see if it has the potential for an overbore. If yes and if you're ready to spend a few hundred dollars, get it magnafluxed, decked square, rough bored and install main studs and align honed.

For the crank, the same idea. Get it measured and checked for pitting in the wrong spots. if its OK, get it ground undersize and you're ready. Depending on machining costs, it may be worth offset grinding the rod journals to get around 3.9 stroke for BBC type rods. The only drawback is your piston choice will be limited unless you go the custom route. Plus, stroking with stock heads may not help that much. If the crank is in bad shape its hard to beat a complete rotating kit from 440 source.

Similar on the heads, get them checked for cracks and valve seat and valve guide condition. If they need a lot of work it will be hard to justify compared to the cost of a pair of MOPAR/Edelbrock/440 source aluminum heads.

If your parts are OK then you're on your way. If not, time to decide whether to look for better stock type parts or upgrade to new aftermarket.