These spindles are interesting. They seem a little hint different from each other. I believe in Andy Finkbeiner's recent book "B-body performance upgrades" there is mention of a lighter later year spindle. I don't really know if this will apply to A-bodies though.

Did you also grind away at the top portion of the spindle on the left?

I would suggest not to grind at these pieces to much being that they are cast to be strong at different points and some bosses are integral to strength.
Be careful out there and study it all before going forward. Measure twice, then measure again just before the cut as they say.

Very soon there will be some interesting ultra super tricks added here and abroad. Keep an eye out.