A new rectifier board is relatively inexpensive. Sure you can build your own if you want, but if you don't want to then by all means you can usually find new ones for $60 at Great Plains electronics. I think I have installed 20+ rectifier boards without one failure so he makes a good product. Your connections are just as important as your board set, and it is cheap to upgrade your connectors.
If I placed a Harlem on location, I would replace all the boards except sound board with new, repin all backbox connections, replace all switches, diodes and capacitors on the playfield, high power switches at the cabinet, remove and clean flipper buttons, replace coin mechs with immonex, service pop bumpers and flippers with new parts. If you aren't going to replace all the switches, do yourself a favor and replace the switch at the saucer. Saucer switches tend to fail before any other switch, I guess because the ball sits on them keeping them closed for a time before ejecting out. Most of this I learned from taking games to shows over the years and seeing what happens when the public plays your games nonstop for several days straight.
Doing the above won't keep everything from failing, but it does eliminate some areas that tend to create their own problems. I have done this treatment to a couple of dozen classic Bally/Stern pins that I have routed since 2010. It has worked well so far keeping repairs to a minimum.