To be honest wth you I cannot blame lupus for your kidney failure. According to you In 1971 you had a kidney biopsy adn it stated " chronic proliferative glomerulonephritis with hypertension". That is not lupus. With or without lupus, your kidneys will continue to decline even once they reached 40%, because in my at 40% they are not 100%.
I have lupus, was diagnosed at the age of 16. THe biopsy confirmed that lupus attacked my kidneys. I had predisone and cytoxin. Without a kidney biopsy to blame lupus, you cant put the blame on lupus. YOu probably do have SLE. But way before you were diagnosed with it, you already had a decline in kidney function.