Trick Flow makes the best low deck standard port intake so if you're going with the 400 block that is what I'd run. It is fairly tall so you might need a hood scoop of some sort.

If you build the short block for the 240 heads then it will be easier to switch down the road. The compression will be a little low with the 452 heads but you can drive it like that for a year or so and then when you have the money you can bolt on the 240 heads and be ready to go.