Joel hasn't said if he's going to be working with the 239/255 Ford/Merc or the 337 Linc. I don't know anything about the Linc but, the 239, is a real challenge.
The first problem, is finding a sound block, to start with. I know of people that have spent more than $2000, just trying to find a block that will mag & pressure test!
3 mains isn't to much of a problem, a girdle and a 180 crank, will solve most issues. Farmall "H" tractor cranks, with welding and machining, can make a 180 crank, for a FH.
337 is attainable but, it takes 8, 3.5" sleeves and a 4.375 crank. The bore centers are 4.000 and 5.125, in the center. If try to go bigger than 3.5, you run into the center exhaust port.
After that, induction and exhaust are the main problems. Not so mush as being a L head but, the size and routing. The intake port, is almost unusable. It's design never changed from the orginal, 221 ci, '32 engine. The intake port, is only 1.312, in diameter and narrows, in the valve guild area, to about .85. As Brent says, the flow is very limited, compared to any OHV engine. I'm adding a actual flow bench test, as well as Ford's drawing of the port. They got this one to 144 cfm. The exhaust ports flow much better but, they are in the cooling system and heat and block, the coolant, as well as being Siamesed, for the center ports.
Using the intake ports, for the Ex is a way to go and make your own, intake tract, with 1.75+ valves, not much you can do, using the intake ports, as ex.
Compression, is your only friend and even that, is hard to get. With the overlap, that you will have, 9/1 should be minimum.
There are modern F head conversions out there but, the Ardun, is the only real way to make hp on a FH.
Like I said, I don't know anything about the Linc, 337 but, it might be a better starting point, although it's very heavy.
In my oppinion, the best hing to do with the original FH, is to build a small 221 engine, for class racing. It's much easier to feed a small cylinder, with what you have available, with the FH.