Magnum Head Valve Spring Compressor

I took the part that mounts on the stud side and cut it, then re-welded it to the correct angle.

Then opened up the part that compresses the spring retainer so I could get the Keepers off.

THEN, after doing all that, it wouldn't work with my new set of springs and not compress them correctly as the bolt was too wide and wouldn't go in between the springs.

Lets just say, if I had to do it all over again, I wouldn't waste my time on even modifying it.

The one like you have in post #9 will work ok, but you will need something to hold the clamps in the springs because they will pop out at a most crucial point. I used one on a set of BBlock springs and there were times when I was ducking parts!!! This type works decent on really weak springs that don't require a lot of effort to remove!!

I would just do like @moparmandan did in post #13 and go this route or find someone with a spring compressor that you can borrow and install them.
Not unlike rocker arms, I had to unjust the "geometry" of the compressor up and down with the adjustment nuts to get a straight down push on the retainers to get the locks on. Too low and it would **** the spring and retainer sideways and make getting the locks on impossible. I learned a little about valve train geometry from this adventure.