KH disc brakes, LBP

The '73 - '76 factory LBP setup weighs a little more than the '65-'72 K-H setup, significantly more, if you use the 11.75" police rotors.

The SBC rotors are available from a number of sources, and are not as expensive as many make it sound, but I suspect you want to change to the LBP for a wider wheel options availability. FYI Summit has SBC rotors for $79, and had a sale in October for $69; slotted and cross-drilled replacements.

The K-H calipers have parts available, where you can rebuild/replace the pistons and seals. Also, there are several outsource caliper rebuilders who can upgrade those calipers to stainless steel bore inserts and compatible pistons/seals. These have a lifetime warranty.

Also, there are some parts vendors that sell rebuilt K-H calipers (Cardone is one of several sources).

If anyone cares to detail the total cost of doing the LBP conversion, I'd bet that conversion costs more than rebuilding the K-H calipers and replacing those K-H rotors.