I've read through a lot of posts but not finding any actual recommendation for a booster. I have a 69 Cutlass w/455 disc/drum set up. The current 11" booster is leaking so I thought I would go with a 9" double diaphragm from Speedway as I couldn't find them at Rock. I currently have about a 1/2" clearance with the valve cover so I could go with any size. This is the one I was considering. https://www.speedwaymotors.com/Tuff-...ch,278180.html. I just wanted to make sure there are no issues with rod length or anything else.
thanks,
Steve

 

Personally I would stay with the original size booster.

 

I would send my original booster out to be rebuilt. I've had good luck with BoosterDewey aka Power Brake Booster Exchange.

 

I installed the 11" booster from Right Stuff and moved my proportioning valve due to the large headers. My setup is working great even with the roller rockers. Good luck on your decision.

 

If you are not worried about keeping the car 100% stock looking, go with the smaller 9" double diaphragm brake booster. It will provide more valve cover clearance, take up less space and provide better power brake assistance vs the stock 11".

The stock 11" is a single diaphragm and has about 95 square inch of area while a 9" double diaphragm would have about 128 square inch. (thanks to Joe Padavano who schooled me on this). The 9" double will provide you with better power braking assistance.