i did it in my 69 and LOVED it! I started with 73 red-dot springs which i was told were the stiffest springs, but later was told in fact they are the softest to start with. In any event I started with 1 coil on each corner (cut off) but ended up taking .75 coil off each front corner also, to try to level things out.
I ran for five years with Bil HDs and the cut '73 springs and never looked back! Great ride and handling.... Spend the $200 elsewhere, like on the Billies..
Nice ride height.....what air dam is that? And are those 14" or 15" rims? I think I am about to cut my springs in the front....just a bit...just enough to drop it another 1/2" or so.....