Exhaust Manifold and Riser Cleaning

I have just removed my engine (1974 Merc 888 - Ford 302 V8) to rebuild the motor mounts and clean paint the bilge. While it is out I plan on taking the exhaust manifolds off and cleaning them. The risers were taken off before the engine came out - some rust inside but plenty of meat left on the walls and passages appear clear (ran water through them). My question is what is the best product to soak/clean these with : CLR, Concentrated Rad Cleaner, or strong Caustic solution??? The engine is in good shape and I really don't know if these exhaust parts are original or not. Prior to my purchase the boat had only ever seen freshwater use. Any feed back would be appreciated.

 

From another thread:

Try electrolytic cleaning. It's a lot safer than fooling around with that acid, it's cheap, and best of all you don't have to scrub.

http://www3.telus.net/public/aschoep...lyticrust.html
http://www.bhi.co.uk/hints/rust.htm

 

By electrolytic cleaning do you mean using a product such as CLR? I was thinking about sandblasting. Any thoughts?