Here's the hard way to fit Austrains bogies into a ringfield motored model. Simply build a whole new chassis out of styrene. Refit the original fuel tank under it.
A bit over engineered, but worth it on the BL or G to get the gap above the fuel tank.
The other way is to simply cut away the original bogie mounting areas and fit new bolsters as below.
And a Lima S class chassis fitted with Atlas bogies. The same as fitting Austrain X class bogies but with different bolster height.
Just cut out the original mounting areas and build new ones. The drive shafts were cut and refitted into a peice of tube for correct length.
You can build styrene motor mounts, or just put the motor in place on a glob of silicone. Just dont use the corrosive ones. Watch out if you use Proto 2000 chassis as they are mostly geared a bit slower than other makers and don't MU well on a DC layout. And don't forget the easiest way to repower Lima models. Just depower them and use as dummies. I'd say 1/3 of my 100s of diesels are dummies!