DO NOT USE .330 bullets in a 8mm Lebel rifle. The bore is not .330 it is at worst .327. Worst advice I have ever heard on here and could possibly kill someone.
.323 bullets work just fine for 8mm Lebel as the first two versions (Balle M and Balle D) were .323 diameter. I personally use the 198grn PPU FMJ boattails myself with pretty good results from my M1907/15.
In regards to the 7.35 Carcano that is a odd ball diameter, I honestly don't know. Not too many people shoot that round to begin with. You might have to look into swaging a slightly larger bullet down to the proper diameter if you don't want to cast.
IMHO you are being more than a bit dramatic here.
I have used Hornady .329 bullets in Lebel cases I have loaded almost exclusively for the past 5 years. They are very accurate. .002 OD is nothing to worry about. If you insist on loading with the bullets touching the lands it might elevate pressures at max loads. The bit of swaging we're talking about here ?????????????????????
As EL17 mentions, .323 diameter bullets work well but not always. Depends on your personal rifle.
Remember, your rifle was designed to work under pretty adverse condition and tolerances were generous. I have only loaded for one of the five Lebels chambered rifles I have for the last few years. It doesn't shoot .323 diameter bullets well but it loves the .329 bullets. I don't load to max specs but to where it shoots the best.
OP, your rifle. You should take your own advice and only shoot what you feel comfortable with. Pressure can be an issue but it can also be worked around if you use your head. If your rifle is in iffy condition etc will make a difference as well.
Let me give you a good example. I have a now deceased from old age friend that used to shoot a Moose every year for the forty odd years I knew him with a P17 Enfield. He never bought a box of ammo in the years I knew him. Why, because he had picked up a crate of WWII Axis made 8x57 Mauser ammo. It chambered in his rifle and shot minute of Moose chest out to 100m. Yes, it ruined the cases, which were Berdan primed, but he never picked up a spent case in his life. Understand, the rifle he was using had a .3085 bore. I remember measuring it because I was concerned by his practice. Didn't concern him one bit. He went on to shoot Moose/Deer/Bear/Elk/Coyotes etc with that rifle until his crate was empty then went out and bought another. This time Yugo surplus and used it until his demise at 80+.
The P17 was found by tests done by PO Ackley to be in the same strength range as the 95/98 Mausers these cartridges were considered safe for. OK, they had to be swaged down .015in and had a lot of freebore to lower the pressures. There should have been issues even then. NOPE.
You don't mention which rifle you are shooting. Check out the pressure limits of the action. They are available on the internet. In this case, your own due diligence is the only diligence that counts.
None of this is rocket science. Surplus rifles are individuals unto themselves and should be treated as such. There isn't a single answer that will fit all of them perfectly.
If you're uncomfortable don't shoot the load.
If you aren't willing to do your own due diligence, err on the side of caution.
Another example, modern 8x57 North American cartridges are deliberately loaded to around 35,000 PSI. This is to accommodate the thousands of rifles chambered for the same cartridge with .318 diameter bullets in case one is loaded in a weak rifle etc. This load is considered to be safe in all such rifles and has been offered for 75+ years. Not so in Europe. You are expected to do your own due diligence when purchasing ammo, where they load both diameters of cartridges to 47,000+PSI.
My suggestion is to load that old girl accordingly with what is available. If it shoots acceptably with .323 diameter bullets use them. If it shoots better with .330 diameter bullets use them but at lower density loadings. This is just common sense.