Nearly impossible to find a clean Salon or Calais that's worth builiding! (and the Supreme or Brougham are just gross with pillow top bench seats and column shifters). The
H/O and 442 also have the quicker steering gearbox, 8.5" rear end and the big sway bars not found on the other cars and the OZ code trans is another huge bonus. The 8.5 rear axle alone these days is going for over $1,000 used. If you found a clean Salon it'd cost close to the
H/O or 442 and require many thousands to bring it to the starting point of the
H/O/442. The only valueable H/Os and 442s I see are the ones that have extremely low mileage and YES you'd be a mad man if you cut up one of those cars.
I don't find LS swapped H/Os and 442s nearly as disturbing as I do when I see GNs LS swapped. I do think a 455 or 350 (Olds) swapped
H/O and 442 actually do the car justice because the 307 was such a slug even with 3.73s and the performance shifting 2004R. But I'm no purist. I like to drive the cars not show them off and have someone judge accuracy of sticker placement.