I've been following along but waiting for the casting number from the block before commenting. It's definitely not an original '62 passenger car 409. The 5J suffix doesn't show up in any of my literature. QJ was a 252hp truck motor though, so perhaps its a glitch and the 5 is just a place holder or a mistake.
The CFD on the back of the block is Central Foundry Division. They started casting blocks in mid-'62. All CFD casting use julian date coding, so there should be a number from 1 to 365 on the bellhousing flange.
It's not normal to find a build sheet in a Los Angeles '62, but I'd look in the rear seat back springs first, then possibly glued to the top of the instrument cluster (above the speedo). Also pull the rear ash trays out and look inside the upholstered panel for one.
Correct that all '62 409s were solid lifter motors and not offered with a Powerglide. That alone might be the only answer you need, providing you're sure the 'glide is original, and not converted for "Mom" from a stick.
Check that ballast resistor and the harness for it. A repro harness will have solder dipped terminals. An original won't.
The fuel line appears to be the correct type, but looks new. That 3/8th line routed under the A arm was also used on all 327 cars.
Back to the Powerglide: '62 was the first year for the alum 'glide and it's a one year only 'glide. Rather than having assembly numbers stamped on the pan, they're stamped in the aluminum bottom flange in front of the pan. If those dates agree with the build date of the car, its a pretty sure bet it's the original which means no orig. 409.
As for the indentations in the radiator top tank, they came with and without them. Full sized Buicks from that era used the same Harrison top tank, only the Buicks had bolts soldered upside down in those hexes for the fan shield to attach to. The hex tops had to be separated out for the Buick radiators, but both types found there way onto Chevy radiators. (it didn't matter)
As for the exhaust appearing original, the 300hp 327 would use the exact same exhaust as the 409. (heads pipes and all). Also, if it's original, the head pipes are welded to the mufflers (one piece)
BY the way, the base trans for the '62 409s was the 3-spd (column) and you didn't get the tach.
Neat car. Great colors, SS convertible, low mileage and solid.
Verne
