Inline twins are easy to cool. You just have to put in your time and build a good baffle system that directs SEPARATE incoming air to EACH cylinder. Done it with a ST60 about 5yrs ago. No big deal to cool the rear cylinder. Just a lot of work to build a good ducted baffle.

I personally think that war bird prop drive looks like a boxcar full of smashed buttholes. It's not rigid enough, it's going to have cooling problems, it's a poor design to bolt the reduction drive to the firewall. The whole front end can vibrate independently of the engine. But, thats just my opinion. So take it for what it cost ya -- nuthin'

Anything can be cooled, if you just build a good duct and baffle system. Don't let that stop you.