The models 46 and 46A where chambered in 9.3X57 and based on M/94 - they have the factory bent down bolt handle.
The model 146 was also chambered in 9.3X57 and is based on the M/98 and also have swept down bolt handle, but the action is based on the military M/98 which originally had a straight bolt handle.
Originally, the HVA rifles were not factory D&T for scope mount before 1953, so it means not before the introduction of the 1640 and the 1000/1100/2104 models. Those are factory d&t for both Weaver type scope mounts and Lyman pattern receiver sights. The 640 made after 1949 have factory threaded holes for receiver sight(a.k.a. 1950 and 1951 High Power models by the Cdn and US importers).
A lot of the older models were d&t by who knows who, and sometimes the wholes are not correctly aligned. Nothing that can't be fixed, but sometimes it's a job to leave to a competent gunsmith. They also need bolt handle and safety modifications to be used with normal height rings.
As for the power of the calibers, the 9.3X57 is commercially loaded to 2067 fps for a 285 graims bullet hich is less than the Whelen. As said above, the 9.3X62 is what Whelen used as a parent "idea" when he made his .35 caliber, so they are pretty close.
1640 chambered in 9.3X62 is a possibility, but they're not plenty here and usually command higher prices (between the standard 1649 and the much desired 1651, chambered in .358 Norma Magnum),
Check out the HVA #### sticky thread for more inputs.