So I still haven't heard back from Hervey about my brake booster and this car needs to be back on the road next week.
I am going to attempt installing a 1979 Saab 99 brake booster in place of my original. I've ordered the part from www.partstrain.com for $138 including taxes and shipping. The advantage to ordering from them vs eBay is I can return the thing should it not fit.