Is the gain worth the pain?

You will gain about 100 fps and brass may last a couple of reloadings more. If you fire factory ammo, you will loose about 100 fps. If you try to resell the gun in the future, you may take a hit on asking price. Depending on the model of the gun, you may experience feeding problems. I've never seen any sense in the .30-'06 AI.

Is the gain worth the pain?

No!
If you just want more velocity,it would be more cost-effective to buy a new .300 WSM or a .300 Win Magnum.
Depending on the action used,rechambering to the 30/06 Improved or Ackley or Gibbs usually requires that the feed lips be modified.
Most of the blown-out 30/06 wildcats were invented and popular back in the '40's and '50's,when the only high velocity 30 caliber was the .300 H&H.Some people wanted more soup without the belted case and high cost of factory ammo.
Some gunsmiths made a good living doing this back when the DCM unloaded a bunch of Springfields and Enfields for $14 - $22,in the late '50's.
We used to call these,the "poor boy magnums".
Most 30/06 factory loads are "loaded down" due to the existence of some "weak" rifles chambered for that caliber.
If you have a quality rifle in the 30/06 and handload it to the pressures that these wildcats are usually loaded to,the difference may be 50-100 FPS,maximum. This was Bob Hagel's position and he tested and chronographed all of these wildcats.
I have a .30 Gibbs so I know where of I speak.
It works for me,but I handload.The next owner will also have to handload.
Ron

Manyplews has said it all in my book. On this question, at least.

What's the point? In the 1950's maybe, but not today. There are simply too many factory choices that represent a notch above the '06 performance to pay someone to dink around with an existing '06.

BUT, I am old fashioned. I haven't found anything that I need to do in the hunting fields available to me that cannot be done rather handily with my 1960's vintage Rem. 700 30-06.

Now if you just want an '06 AI because you just want one...then go ahead. "Because I want to and like to," is adequate justification for a project like this.

I built a 30 Gibbs 10 years ago and I did it for one reason. I was going to do alot of backpack sheep hunting. I wanted the gun to be light with the balistics of a 300win mag without the mag bbl. I bought a browning A-bolt composite stalker and had it reamed before I even shot it. I shoot 165 Barnes XBT at 3050fps and it is a tack driver. I would not trade this gun for anything. I have shot elk ,grizzlys,deer,and antelope with it and I love it. It will be buried with me! I think that if you are doing it strickly for balistics umm...maybe not but if you want something different that you can use for everything, well then go for it!!

ABSOLUTELY NOT~!!!

This is one wildcat that just doesn't have the claws!

Here is a snap shot to give you some perspective. At the left is the standard .30-06. The Ackley Improved in the middle and a .25 Gibbs on the right. The .25 is not exactly a .30 Gibbs but give some perspective
Edit: I forgot to give my pal ENGLANDER credit for help with the picture taking and file attachment!