Welcome to the forum, Mike. You've got a great start with that block. First suggestion: Go with the stroker kit, like everybody else
There is a reason they are popular. Number 1, you aren't using old parts. Eventually old, used parts will fail. Number 2, the BBC bearings in the stroker kits are wider and smaller in diameter than stock FE bearings, giving you more load surface and less bearing speed at a given RPM. Number 3, cubic inches rule, especially on the street. If you think your friends 428 has an immense powerband, wait 'til you feel a 482" FE powerband. Number 4, a 4.25" stroker combination is easily capable of 7000 RPM, and will pull hard all the way there. If you are trying to build a real winder, a shorter stroke crank will let you go higher, but you'll still be down on power because of fewer cubes.
On the heads, the 1.66 valve will work fine, but I guess I'm not sure why you don't want to go with the 1.71. That valve would be a better match for your 2.19 intake. You should be able to get 300 cfm on the intake side with those heads, making over 600 HP do-able with this combination. You should not have to open up the low riser chambers much, if at all, to get that flow number.
I would go with a 2X4 intake, probably the medium riser dual plane 2X4 manifold if you can find one (factory or Blue Thunder; they both perform about the same). And you will want a bigger cam than a 294S; more cubic inches will require more camshaft. I would consider a roller cam, like a Comp 308R or maybe a hydraulic roller, although the hydraulic roller probably won't let you go to 7000 RPM.
There, I've just spent all your money for you
600 HP, here we come...