I don't know if this will help you but......
My 88 ST600 converted to 700c measures 370mm from the top of the fork crown to the center of the axle,
ridden hard, well worn and well loved.
I certainly appreciate the data point! Another user on a Cannondale FB group measured the same on their 91 ST1000. Wondering if all Cannondale did was add canti studs to the caliper brake fork now.