I don't think anyone thought he wanted overloads. However exceeding the SAAMI limit is by definition an "overload".
It is only an overload for the case and not the rifle action when considering the .35 Remington round in the 760.
The .35 Rem brass is not very heavy in the side walls. Factory loads in my rifles tend to show a mild pressure ring about 1/4 to 1/2 way around the case head at the junction of the solid head and the case walls. The .35 Rem data for the Contender pistol runs about the same as rifle data to about 2 grains heavier with some powders. In my rifles, a 1952 Rem 760, a 1946 Rem 141, and a 1952 Marlin 336, an extra 2 grains of 3031 will show a little bit heavier pressure ring for 360 degrees of the case head.
Loads using 4 grains of Accurate 2015 over maximum show a sharp pressure ring expansion. Please note that the Accurate Manual shows very low pressure (27,800 PSI) for this powder for the Speer 180 grn bullet. While the case is expanding a great deal more than a factory load the pressures are still low based on primer appearance. However such loads will shorten the life of the brass.
Most people don't have pressure measuring equipment. Pressure measuring equipment does not know what is happening to the case. I know the case head pressure ring is not very exact or scientific. When there is no other method, looking at (and measuring the pressure ring) can be better than nothing for estimating what is happening to the brass.
.35 Remington brass was readily available 20 years ago. About 15 years ago it started getting a little bit more difficult to find and by 10 years ago was very uncommon.
If you want your now hard to come by brass to last you should look at the pressure ring at the junction of the case head and case walls. Keep the ridge about the same as factory ammo.
If you have no ridge and your primers are backing out you might want to up the load a grain or 2 to maintain the shoulder position to prevent head separations.
I would recommend you set your shoulder to the longest possible length that will still function in your rifle. If you decide to hunt with loads a few grains hotter than the manual use those loads only in cases of known good condition.