Might be shootin' myself right square in the foot here, but buy all the high condition model 70 post 64's up to the early 80's that you can afford.
They are cheap now, but in won't last forever especially in the odd calibers.
How many people were buying pre 64's in the 70's?
How many wished they had?
Everybody knows what is hot, the trick is to figure out what is going to be hot before it is...
