We changed out an Atomic gas engine to a Volvo some years back.. the beds were at a different angle and spacing than the Volvo required. As the beds were wider, we cut them down to the correct angle, and installed fairly heavy Aluminum 'angle iron' inside each bed to achieve the correct spacing. In the end it worked out fine, but was a bit of a nasty job, esp the cutting of the solid beds.
Anything is possible with enough ingenuity and courage!!