I had a slight advantage, I did a BHG repair then 5 months later the Big ends went so I had to remove the engine. Whilst waiting for parts I decided to clean the engine up (as you do.)I used a combination of general household cleaners like Flash and Mr Muscle etc just did a bit at a time. I re sprayed the bock and any heat shields with high temperature silver paint although once I replaced the engine its hard to see.