I think I've said this in other OD posts, but with my a500 conversion I found the
#71V2. Universal adjustable vacuum switch
to be very hard to dial in, tiny amount of rotation of the set screw made a huge change, I went back to the GM one.

Also, the adjustable line pressure switch vs. the set GM ones are very nice. If you do a performance build on the tranny and jack the line pressure up, the GM switches will have you into OD by 35mph. I have a '62' GM switch on the OD that actually shifts at a true 45mph on my car. I have one of the adjustable ones for the lockup side that I have set to not come in until 55mph. The car is MUCH more responsive when set up this way and you don't bog the engine around town.