Measured and drilled the main gear supports. Mine were pre-cut to just about the right size, so I didn't need to trim the length. The pads did need to be trimmed to 5.75" before the notches were added to fit within the weldement. Used a die grinder rasp to make the notches in the pads.
My wife helped me test fit the main spring, which came pre-notched. The notches seem to be slightly too close together to fit. Used a piece of L angle to mark the centers of the studs and compared to the notches in the spring. Looks like both front and back notches are off by 10mm (5mm each side). Sent Roger an email to see if it would be ok to extend the notches outbard by 5mm each.