Yes, we'd have a LOT more representatives. But we also now have the technology to support such a thing.
> As a result [of the Reapportionment Act of 1929], the average size of a congressional district has tripled in size—from 210,328 inhabitants based on the 1910 Census, to 710,767 according to the 2010 Census. https://en.wikipedia.org/wiki/Reapportionment_Act_of_1929
So then all the Senators should just be from California, Texas, New York, and Florida.
But you can clearly amend the powers of the Senate, including abolishing all of them. And/or create a third house of Congress, without equal per-state representation.
First of all, you have no idea what you're talking about. The two Dakota territories gained statehood in 1889, long before there was any kind of notion of the modern-day Republican party.