Budget limits always get ridiculously convoluted because someone always brings a "sweetheart" deal or a "junkyard find".
I think keeping it the simple is better for the first go around is the way to go and that is either keeping OEM blocks/heads/single 4150/10.5 comp /flat tappet lifter and a narrow cubic inch range because we all know a '906 head won't feed a 440 the same as it will a 383. J.Rob