C2 LS restomod: power brake options when there's no room for a vacuum booster?

Options from Speedway's booster and hydroboost guides:

• A single-diaphragm booster: shallower than a dual-diaphragm unit of the same diameter, which often frees up room in tight bays. Single-diaphragm boosters suit drum or disc/drum systems; four-wheel disc brakes usually want a dual-diaphragm unit for the higher pressure.
• A smaller-diameter booster: fits tighter spaces, but less diaphragm area means it needs more vacuum to give the same assist.
• An electric vacuum pump: makes sure the booster gets enough vacuum and can mount almost anywhere — trunk, inner fender, crossmember — with just switched power and ground. Useful with a big cam.
• Hydroboost: uses power steering pressure instead of vacuum, but the CPP units are about 22 in long, so they don't solve a short-space problem.

Measure the space including the master cylinder before choosing.