I have been collecting gen III hemi stuff for a while, but my heart has always been with the Gen II.

If I start with a Mopar block in a 4.240 bore, what should I build out of it? I have no ET goals in mind. Here is what I do want:

Room in the bores for a rebuild or two in several years.

As much compression as 93 pump will allow

HAS to have a cackle-y idle.

The car is a 1968 Charger, no trans or rear end yet so I can build what I need.

Thanks for anyone who has been here before me!

Call Ray Barton. He can spec in your reciprocating assembly and cam.

No good reason to start with less 4.500" bore. It's free power. And it helps everything. And there will still be enough cleanup room to last a lifetime. And a 4.150" crank. That will be a 528. The last one I built was a 4.250" bore. What a bad idea. I had a new rotating assembly laying there so I thought I should use it. I should have thrown it in the trash. More cubic, better heads and modern pistons are why Hemi's are 800 HP today instead of 425 HP. Don't put together a dog.

Those Edelbrock heads are stupid cheap (like wedge price complete) too and I think they work better with a 4.5 bore?
I ran 426's for decades and the stroker deal is what really makes a Hemi work nice on the street. I've built 472's and 528's and either work better for a street car than a 426 obviously.

I would start with a 4.350 or 4.375 bore with a 4.250 stroke crank with BB Chevy 2.2 rod journal sizes, 7.100 long good steel H or I beam rod, your choice, a camshaft with between 250 to 270 degrees @.050 with as much lobe lift that you can get and have it ground on a 109 to 111 LSA and install it between 3 to 6 degrees advanced in the intake lobes
On the pump gas compression ratio shoot for up to 10.5 to 1 with iron heads and 11.0 to 11.5 to 1 with aluminum heads

Thank you guys, I just took the plunge with my wallet! I appreciate all your advice, I will be asking some more questions soon I am sure!

I would order the bores undersize no matter what diameter you decide to go with and have a good machine shop take them home,
If you order the bores on size and they need to be fixed (and they probably will) you start running out of available rings for rebuilds without boring the cylinders to a larger size.
Also if your going with a large valve head 4.500 is your min bore size. IMO

Larger bore makes more effective quench.

I ordered the 4.24 rough bore from Jeg's.

I have been reading the posts and I understand that some form of stroker will be best.

Does anyone have an idea of how much HP these blocks can live with? I am sure I will be under the limit, but I am curious to know.

I've never heard them say how much power they can handle but as you said it's a lot more than you or I plan on making.

I like to start a new block at 4.440 bore. Leaves 2 overbores.