I don't know about anything about Staton's FD unit, I don't know the proper spacing for that unit.
But the DAX and BMP FD units like the 7/8" spacing, never had any trouble with them.
The DAX engine is a copy of a Honda, I believe. I don't know which model of Honda exactly, GX50 or something like that?
Any Honda small engine dealer should be able to get you the springs, or look here:
Honda Engines - Small Engine Models, Manuals, Parts, & Resources