What metal conduit takes a 1-5/8" dia. knockout?
1-1/4" pipe  (which are also IMC/RMC sizes) are 1.660 OD which is pretty close to 1.625. The thread start diameter on the narrow end of pipe threads is 1.557 so a nipple ought to get in the hole even if it's just that size. EMT fittings (on the threaded part) are normally threaded the same as the pipe/RMC/IMC size.

One of those weird pulling elbows is the only sharp turn I know of in conduit, other than using a conduit body, or a box.