5.8cm 1.4 NIKKOR

SEEMS LIKE I CAN HAVE ONE FOR COLLECTOR PRICES BUT ARE THEY MARKEDLY DIFFERENT FROM THE ORIGINAL 1.4/50 THAT I GOT ON MY CAMERA IN 1970?

There's not much information about the 5.8cm f/1.4 Nikkor online. What there is suggests that it was a good fast lens for the time, but that it is the rarity of the lens, not the optical quality, accounts for the pricing. I've never used one...

Ok this is second-hand information but from a reliable and experienced user.
A friend of mine used the 58mm f1,4 and the 50mm f1,2. He preferred the first one for 2 reasons:
1 his second lens was a 35mm so he claimed the 8mm difference from a standard 50 was visible.
2 he said the 50 f1,2 was a real bad experience, having (I quote) less sharpness than the f1,4 and even f1,8. Too soft for landscape, ok perhaps for portraiture, Hamilton-style he said with a funny expression on his face...

I have one, and yes the 8mm does make a noticeable difference in the field of view. It's a good lens, but I think the newer 1.4 50mm ones are a bit sharper. It is one of the first ones made and is a good match to my very well used early F with the Photomic meter that isn't a ttl one.