The '39 looks like a good deal for a good car. The 1939 120s retain the 1930s styling and offer an improved cooling system and full-steel body construction with improved body sealing against dust and noise.

Concerning tire pressure:
Owner's manual or shop manual pressures for your specific year and model and body style should apply to any brand tire of the same construction and size as original equipment. I tire pressure specs usually assume a full passenger load, with tire pressure checked cold. Later models with "balloon" tires on drop center rims often had very low tire pressure recommendations, such as 22 PSI for 1937 120 coupes. Adding 10% to that is probably a good idea. Earlier cars with "clincher' type tires and rims had higher pressures specified, usually 50 PSI or more, and it is not safe to reduce the recommended pressure by any significant amount with clincher type tires and rims.

You don't want ANY restriction in your lower radiator hose. It's best to use the pipe arrangement with a smooth, full-diameter bend and to use pipe the same OD as the OD of the radiator and water pump connections. Using the pipe and short lengths of straight radiator hose eliminates any need of an internal spring, and it assures full, unrestricted coolant flow. Stainless, mandrel-bent pipe would be ideal. Or brass. The original pipes were mild steel. The bend, or curve, is a little more than 90 degrees.

Mine does have a flange with single bolt at the block, then the tube extends outward and curves 90 degrees, then straight down to a small bracket on the clutch housing. A picture would be very informative. One of the engine views in the various service and advertising materials in the archive might show it.

That is the slip yoke. It needs to be assembled correctly, or you can get vibration due to incorrect "phasing" of the U-joints. In many cases, the slip yoke spline can be inserted in many ways, but only one is correct to put the front and rear u-joint in the proper relationship to run smoothly. If you clean up the two halves of of the slip yoke assembly and look very carefully, you will may see an arrow and a mark stamped into the metal. The arrow and mark should align.

Is the cover aluminum? Perhaps it has a crack in it.

From back to front at the center, my package shelf is 17 1/2" . The cushion and backrest angles seem to be typical. I don't think I could lean the seat assembly forward enough to move the whole thing back much. I haven't had the top down to see how much room it would need behind the seat. The seat tracks look like new, but are stuck. I'm pretty sure they're stuck all the way back.

I was able to move my seat back against the package tray, but that's still not enough. I'd like to move it back another 2" or a little more. The seat cushion is too high to suit me, and the seat is too close to the dash.

1948-1952 Ford pickups used a very similar item to the same purpose. They riveted it to the inside of the flat door post, but the part itself may be adaptable. I think Ford vehicles used that type of thing from the late 30's up to 1949. The passenger models may be mounted like the Packard.

85+ PSI sounds high for an earlier car. Ethylized gasoline was not widely available in 1930, if available at all, and low octane, low volatility, kerosene-like fuel limited allowable compression, even with improved Ricardo-type heads.