First, where are you getting the number "97-1284?" Part number 1284 is too low to have originally been a "97" number. It is more likely to be "H1284."
Second, is the number you quote cast onto the fork tree? Often, Triumph casting numbers are one or two numbers away from the actual part number. The number closest to the one you quote is "H1283" which my parts books show as being the lower fork tree for 1960-62 duplex-framed pre-unit 650 Triumphs.
I may be wrong on this, but that is my closest guess.