Also, the Senate used to be chosen/voted on by the STATE's congress/senate, not by popular vote, which was only for the House. Overall, even considering all the corruption, the system still works pretty well. A minor miracle.
I would go with the original Constitution on that too. Arguably, the only amendments (beyond the first ten) that were even needed, were the 13th, 14th, and 15th, which addressed the condition of freed slaves. Possibly only the 13th Amendment was needed. The original, unamended Constitution only addresses voting for the House of Representatives. It doesn't address who can vote and who cannot.