a 58cm is not always a 58cm. I ride a '59cm' and the TT is 58.3cm c-to-c.
You will lose big power if your saddle is set too far back or your center of gravity is not correct due to longer stem, etc.
Oh, sure. you could make it work, but the #1 key to riding is comfort & function.

A good deal on an ill fitting bike is not a good deal.