A 360mm lens is impractical for 5 x 7 enlarging.
To make a 9 wide projection of the roughly 4.75 wide image rectangle of the negative requires about 1593mm from the negative to the print and the center of the lens needs to be 549mm from the negative.
You'd need 2109mm from negative to print to make a 17" wide image for a 16" x 20" print.
These approximations give us a reasonable idea of the distances needed.
You might get the needed negative-to-print distance by obtaining the horizontal projection brace for the 45MX and project onto a wall.
A greatly extended lens mount (a long lens cone) could be fabricated to fit the 45MX, but its not practical with such a long lens. A much better choice is to obtain a 180mm or 210mm lens. These are designed to fully cover the 5 x 7 negative at any practical magnification.
Last edited by Ian C; 12-13-2011 at 02:02 PM. Click to view previous post history.