Iffy. Contact RIA and ask them. Don't know if the ejector will fit.

The dimensions are not the same, Leroy. Even if they were, consider that the frame itself is designed to handle certain pressures when fired. The 45acp cartridge will produce much higher pressures than the 9mm, and therefore would be deemed unsafe.

No, You can not go up in size. Some firearms will allow you to go down but not up. There are different sizes for the bigger rounds

no while the slide will fit it will not work. the feed ramp is made as part of the frame and will not work for another caliber. the ejector and springs would also need to be changed

Leroy, no Sir. The slide dimensions are only the same for .45ACP and 10mm. Cheers and stay safe!