The way I did my car the change in height was less than 3/8” from just the slider swap over. Since it was all from the rear it would definitely tilt the yoke down a little more, but it would be a fairly minor effect. I honestly didn’t check it again after the slider install and didn’t have any vibration issues. Probably not the best way to have done it but that’s what I did.
My car has a B-body 8 3/4 in it though, which have their pads welded at a different angle than A’s did anyway. I checked it all and shimmed it to the correct angle when I did the T56 install, but that install obviously changed other variables too.
If you’re building brackets there’s no reason you couldn’t make them a bit taller to keep the rear eye of the spring in the same place with the slider install.