klz......here is an image of your MSM Clyde oscillator

........
Why not e-mail the manufacturer here in OZ... and ask the begging question........
[you should really nominate the planned angle of inclination to expect a sound response comment]
http://miniaturesteammodels.com/category26_1.htm or
Email: info@miniaturesteammodels.com
Website
www.miniaturesteammodels.com youtube
https://youtu.be/4lGon6ydw1kIn lay terms, one would think that a pair free floating bronze/brass spacers [to take up all but a few 0.001" of longitudinal float] located on the crank shaft as shown would be sufficient

..... the Manufacturer may also consider the pair of piston rod bearings on the crankshaft pins must also be adequately supported ??
Additional lubrication would be required at each run, but a few drops of oil from a plastic needle
oiler should suffice but again, [the
dark green is steam oil]
Pease let us know the response, as it is a question that a number of builders could face
Derek