From reading I've done it seems real old Firebird pickups were a peculiar creature. Top is your mini-PAF Deluxe type with screw poles/slugs and single magnet Real 'bird pickups used small bobbins with Alnico 2 blades. Most modern copies don't. I've had success swapping alnico magnets into various ceramics, in my Setzer Hotrod for instance. The MIJ Filtertrons had the right wind and I swapped in a pair of PAF magnets in each, which are the same width/length but half the height. They sound great. I found some Firebird knockoffs for $15 a pop measuring close to originals . I am building a 'bird into a Firebird VII clone like this one. So I got three gold pickups. Got six Stewmac alnico 2 blades for $50 including the steel plate and metal tab to bridge the magnets over the B-G string. Use my Leatherman to cut the cover solder. Inside, two bobbins wired series and a ceramic magnet bridging two blades up inside the bobbins. That's the ceramic magnet and two blades. Alnico blades are helpfully marked red in North side so this is a N-S pair. You can carefully push the steel blade out with the new magnet. Here's the new magnets installed. The bobbins are slightly taller but that's not a worry. I just push them to the top. I just have to make a 5mm wooden shim to take place of the ceramic magnet. These bobbins were potted too. A stainless steel plate goes underneath and a small tab across the two bobbins over B-G string run. Solder cover back on, job's good. About 7.5 Kohm DC resistance. Genuine old Firebirds are 6.5-6.6kohm. I won't get the body for a while but looking forward to trying them out.