Manual to Power Conversion

I have a 75 Duster Custom Slant 6 with drum brakes all around. I want to convert to power (add a booster) given how hard I have to push to stop. Original master cylinder is a 15/16” bore with two equal sized reservoirs. I purchased a master cylinder/power booster combo from NAPA (see pics) but from reading this forum, it’s for the frond disk break setup (it may be for sale soon). I want to eventually convert to disk in front but that’s a future consideration and I know I may have to replace these parts again. Questions are:
1. What do I need to bolt the booster to the firewall? In another post, someone mentioned an adapter plate that goes between the booster and the firewall. Where can I get one of these?
2. Do I need to change push rods, anything else?
3. I see in other posts that some of you think manual is better. Why?
Thanks!

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Author: admin