Ok i thought i would check now anyway
RM 125 B chrome fork legs are different part number the 125 C fork legs
RM 125 B outer fork sliders are different part number to the 125 C sliders
RM 125 B fork springs are different part number to the 125 C springs
RM 125 B damper rods are different part number to the 125 C damper rods.
Now this is based from
www.alpha-sports.com if you have 125 B and 125 C paper parts books or microfiche that says the above parts are the same part numbers then, you have proof in hand to show the scrutineer and you will be fine
. If not and you decide to use the 78 parts and want to race pre 78 be prepared that you could be protested against. The part numbers are different according to the website so in my opinion you would have no argument as the part numbers are different and its in black and white.