Hiya, I think there are very few products available which will give super results especially with the carbs in situ. I've tried all the Halfords stuff plus thinners,acetone,autosol etc. etc. but nothing seems do do an easy job of it......or even make a difference.
I'd still strip the carbs if I were you seeing as they are off, although you say they were in great tune it's the balancing levers/adjusters in general that see to that.............those settings will be lost now anyway.
Strip them down completely....things can only go back the one way so it's no risk.
Degrease the carbs with a general degreaser then Jet wash them off.
I then used a chemical from a firm called Ardrox (basically a pickling paste), which although nasty stuff gets all the scarring and deep grained staining off bodies........just spray it on, agitate it and wash off.
Final step was then soapy,mildly abrasive household scourer with carbs in the sink
........came up like new.
A good blow through with compressed air and job was done.
Finish off any brightwork, nuts,bolts banjos by either having them plated or buy new from a guy who calls himself "fastroadcars" on Ebay, official weber dealer and a decent bloke...............I bought the refurb kits off him too..............I think he ships abroad but worth an ask.
A similar thread came up last year whilst I was doing a set of 45s and I posted a pic...................I'll re-post the same pic to see what you think.
Again, dont worry about the carbs going out of tune as they all ready are, stripping them will make no difference.
Cheers,
Kenny