That spread of images brings back memories. Where I grew up one guy bought the 301 adapter from Honest Charlies and a pattern was made from it. I can't honestly say if the adapter was actually returned, or not, though there was a rumor floating around it had been and the buyer got his money back. Pilot adapters were bought by a whole bunch of folks who flame cut their own adapter from flat stock in the School Shop and bone yards were picked clean of Olds and Caddy engines from miles and miles around. It was like a revolution in motoring. I ended with an Olds in the Forty I drove to High School. Looking back, I can't say for sure if it was the adapter being off, or the pilot bushing adapter that was re-created on a lathe in the same School Shop, or not, but it was like living with a monster. One that ate transmissions. It might have been the lead transplant I had on my right foot earlier on, I can't say for sure what was the culprit but to the poor soul who believes a hot rod can be had using a '39 top-loader behind even the most tepid GM overhead of that era, let me warn you that after thirteen (13) transmissions I gave up and bought a '53 Chevy. I was tired of walking and spending all my money re-building those that were buildable and scrounging up good used ones. I reasoned, of course, as many will that Lincoln gears might have fixed my problem but didn't have the resources to find out. My suggestion is to use a later model four, or five speed, built to handle the torque. Traditional is good and all that but there is a world of difference between a flathead and an overhead when you pop the clutch. And, to those who say you have to learn to drive it with reason, I can only say, WHA? That's what Granny does.
Speaking of making your own, a friend of mine replicated a #403 adapter to bolt a hemi to an early ford. He took a piece of steel pipe and welded 2 flanges on it and that was it. It actually did work. This was early '60's when the $42 for the adapter was about 3 days wages.
Where did the myth come from that 'Lincoln gears are stronger than Ford'? An old guy told me they were 'wider'. I changed his tune when he dropped by to see my gear collection. "But they ARE harder," he contended. Harder to find was all. RATIOS were the Lincoln's call to fame. 25 tooth were favorite, 26 a close contender. Close ratio cogs. Period. Now, if the '68 type 3 speed top loader were available then, with the Jeep tower....different story. LaSalle bolted right up to that Caddy/Olds. Bellhousing and clutch, Cad/Olds parts.
The Jalopy Journal
