A153 ssbc conversion?

thanks for the response. I actually am running a smaller purple shaft. 484/284 to retain stock rocker gear. I am happy with power brakes. Factory 7" dual diaphragm booster. My brakes all of a sudden got hard. believe l need the booster overhauled. Company in stoney creek Ontario quoted me $400 plus tax to rebuild booster. 727 auto in gear, only getting 8" vacuum. My car is in storage till spring so just thinking what are my options.
My dart l swapped 20 years ago from drums to k/h manual discs worked great. Want to keep sbp and my 15"cragars. Always had small block 3000 lb.a-bodies.