[Scramblejams]

Upsides are that they're both first- and second-order naturally balanced, requiring no balance shafts, which reduces weight and makes them very low vibration. I keep waiting for someone to come up with a lightweight, turbonormalized straight six that runs on Jet A to replace old turboprop engines on aircraft, but I digress...

[GenerWork]

Question about that, wouldn't packaging be an issue unless you really shrunk the engine size? I thought that's what makes LS swaps into planes so interesting because you get a fair amount of power in a small package.

[Scramblejams]

You're right, packaging would definitely be a challenge. The cylinder head would need to be low profile, conformal exhaust headers, dry sumped, and put all the plumbing you can (including the turbo and wastegate) behind the block. Maybe it’s not feasible, but it sure would be an interesting puzzle to try!

The peeps I've talked to who've done LS swaps seemed more interested in the economic, technological, and fuel economy leaps made versus the certified air-cooled default choices rather than the power, but YMMV...