IMO...... The real first step in this process is figuring just what the budget for the complete motor is(carb to pan, dist, wires, plugs, oil, everything), and see if what you "want" for an engine combo can be done competently for that amount of money.
Sometimes(often times), the budget and the desires aren't on the same page(filet mignon tastes with a McD's budget).

In that situation, the budget or the build goals need to be adjusted to make it all work.

In the end, it usually comes down to what can you spend....... And what's the best build you can do for your requirements that will fit within your budget.