Hey there Dan,

Sounds like you're thinking about a project. You might check out the MSN groups forum for Ford flathead 1932 to 1953. They have all kinds of info archived in the techno site on the left margin of the page.

http://groups.msn.com/FordFlathead19...3/general.msnw

Basic answer to your question is they do bolt on, but it's not a simple swap. There are a couple of contrary coolant holes that don't line up. You end up plugging one or two. I've read about it, but haven't messed with it.

The early heads have seen some pretty creative thermostat solutions, basically what the guys that run early engines have to do anyway. Everything from capturing the rim with screws thru the neck to using zip ties above and below a t-stat in the hose close to the head. This too, is covered in the Techno site notes.

Lots of guys are running HEI systems with late heads. Another similar option is to go with MSD setup that is made for the 8RT/8BA engines. Only advantage to a modified HEI from GM is cost savings. Techno notes cover this topic also. You'll find super flathead guys on that site.
Tim