Thanks again for all the input. I have the latest numbers just to update the post. I spoke to the plaster installer and they recommended against the 20 gallons of acid just as you all did. The areas of scale are still smaller than before.
FAC 4
TAC 4
CH 200
CYA 99
TA 80
pH 7.6
TDS 1450
Pho 300

Thanks again for the help.