Hey Brickman;
I have long been wanting to put one of these in something. I'm probably looking at running it in a custom woodie phaeton I'm collecting parts to build based on a long wheelbase and old auburn or cadillac chassis.
I have a totally rebuilt one sitting on a cradle in my garage. It too is out of a 39 caddy, a 75 formal limo, I sold a guy. The previous owner spent over 3500 on the machine work and parts 15 years ago. It was built by a shop that does race engines and I know they bored it but I can't remember the specs. off the top of my head. I did score an edmunds dual manifold a couple of years ago for around 200 with carbs. The stuff is out there just kind of limited and some of the people think what they have is gold.
I did have a 38 model 65 if i'm not mistaken sedan that ran wonderful. It had a 41 engine in it. It had quite a bit of top end and even in a 4000 lb car still went quite well I had no problem passing a newer car that was running 60, I was doing over 75 by the time I got past them. I'm more for tall gears and bringing down the revs than burning rubber around town. I think the motor has lots of potential but not for drag racing. I have a friend that does fabrication that has been itching to try and make a mechanical fuel injection for this engine. That would be wild I think. Of course lots of thought has been given to the headers. I think this could be one fine looking engine if it was all put together right.
Sorry I rambled on a bit. I was told that the 39's had a design flaw. I'm not sure what it is though. I know mine was magnafluxed before they rebuilt it.