Ya know I bet that BBQ/Can method would work great..

I've had great luck with the crock pot pre-heated on low and a short 1-2 hour soak..
I used straight green glycol based AF..

I pull the carb if it's loose and working..
If it's gummed up I'll strip it down as much as possible without forcing anything, hang the parts on a wire loop and soak em with the motor.
Pull the back plate muffler and the glow plug.

When it comes out I'll blow the motor out with compressed air.. Do it outside.. you'll get AF vapor everywhere and wear a heavy glove.. The motor will be HOT!

Re-assemble, lube everywhere inside with ATF and spin it over several times..
Install the plug.. check compression.. Run as soon as possible to boil off any remaining water from the AF.

I've done 5 motors that were in storage for 15 years.
They were totally castor locked. Now they all run great.

Saito FA-45
OS Max-S .35 RC
Super Tigre .51 (Older motor made in Italy)
OS FS-61
OS .45 FSR

I tried some gas motors just to try and clean them up but it didn't do anything for them..