I have many butterfly koi and I have some with scales like yours. Your longfin is a doitsu. They usually have scales down the dorsal line, sometimes also the lateral line or sprinkled in other places like yours. The large scales are called mirror scales. Some koi have these large mirror scales all over.
My female koi that I spawned this year is probably 4 or 5 years old. This was her first spawn. The males are probably between 5 and 10 years.
My breeding tank was 700 gallons, I think (1000 at the most).
I filled it to about 18 inches deep and put in a 30 foot spawning rope and a few filter brushes.
Don't apologize for asking questions. That is what we are here for.
I said you should breed her to a wagoi (scaled) butterfly koi, because when I bred doitsu to doitsu, I lost all of the fry. I have read that doitsu x doitsu sometimes results in high fatalities of fry due to genetics.