I never tried, but have switched around on other bikes. As long as the eye to eye lengths are very close, the mount bushings are the same width, and the mount bolts are the same diameter, that would be a good start. The Suzuki shocks are probably made by Showa anyway, so are the STs.
Good, used (<10k miles) ST1300 shocks are not plentiful, or cheap, in my experience.
Of course you would need to set up the preload, sag, etc. I would guess the Suzuki is a lighter spring than the stock ST1300 shock.