For what it is worth...
I get a lot of painted engines and it seems different manufacturers paints have different tenacity.
Honda silver flies of as does most Yamaha cases, where I have had Suzuki's to blast and it has taken longer.
If someone has already painted them with two pack it can take even more work.
I have had parts brought to me that have been Carbolene bathed and it has definitely worked.
I am currently searching around for a decent depth stainless tub for a full Methylene Chroride bath - five minutes in this shit and it's 'paint no more' but requires a lot of care both in use and monitoring progress plus a well ventilated area to handle safely.
All seem to leave the odd patch particularly at the bottom of the nooks and crannies where the blast stream requires more time there but it all comes off in the end.
I'd be careful of molasses - try around 1 to 4/5 and use a sample, say a broken side cover or piston that can be chucked - molasses is great on rusty steel but I am not sure about what it would do to alloy !?
Dave Mac