Brake Upgrade for M172A1 Trailer

Anybody have any experience with upgrading the brake chambers on an M172A1 trailer? I need to go over the whole thing and will probably replace all of the brake lines. The trailer does not have spring (dual chamber) brakes and I would like to have that feature. Other than adding a spring brake valve, and new brake chambers, anything else I need to consider? Will standard brake chambers fit? The trailer is a 1967 Fontaine. Looks like one (or three) of the chambers has been replaced already, only one is bolted together.

Type 30 brake chambers should replace your bad chambers . and the right valve will set the brakes when the truck air lines are unhooked or the air pressure drops from the truck . This trailer may already have this valve it's just full of rust .