Having one power coated with clear is probably the best way of keeping the original sand cast aluminum looking great, but won't the 400 or so degrees for power coating warp the manifold?

you can try this stuff, a lot of guys use this on the heads, they say it don't burn off where the exhaust ports are, and it only takes 350* to cure, which should not warp the manifold
https://www.kbs-coatings.com/XTC.html

Or you can use this stuff, no heat to cure, and it comes in Satin or Gloss but it says
(Great for high temperature automotive applications including the use on cylinder heads, engine blocks, brake components and even inlet manifolds, without yellowing up to 250° Fahrenheit.)
I would be afraid of the "without yellowing up to 250* F" I think the intake might get hotter than that in some places
https://www.kbs-coatings.com/DiamondFinish-Clear-Aerosol.html

I have used their XTC paint on a set of headers with great results, I will be using it on my intake as my intake will be sandblasted so it won't have the factory new finnish, the Aluminum color is pretty close.

Actually, I got that Diamond Coat from Eastwoods a ways back and I use it to seal all my raw shiny metal parts. In fact, I sealed this same manifold but I wasn't expecting to cope with outdoor storage for a long period of time.

I went Internet surfing last night and found that it's pretty common to powder coat intake manifolds after bead blasting to clean them up.

Yes, I had my aftermarket aluminum intake manifold powder coated. Silverdillo with clear coat. Looks great years later. Keep the gas off of it but would do it again in a heartbeat.

Not an intake, but I recently had my hood hinges blasted and powder coated. BIG mistake. While they came out looking incredible, I basically glued the joints together. Had to squish them down to function, exposing all the un-powdered areas.
Lesson: you must take apart moving parts to powder coat, and if they have rivets, like hinges, dont bother, 2K would've been way better. Dope.

The hinges are not to be painted. If you have a lot of friction between the hinge joint your going to seize the hinge and bend the hinge flange. The hood will look popped up at the rear.