I must admit that I find that I can get most if not all my heavy-ish distorted tones from my 2204 JCM800. This not least when combined with a suitable booster such as the TC Booster Line Driver/Distortion.
The TC BLD tightens the amp up VERY nicely and brings it nicely sonically a bit more up to date and gives it more versatility. It obviously still sounds very much like a Marshall no matter what you do, which is fine by me.
One of the things to be aware of with the Marshall JCM800's is that there are BIG differences between the different models. This is not just between the single channel JCM800's (the 2203 and 2204) and the twin channel version (which are the ones that use diodes for the overdrive channel), but ALSO within the range of the single channel 800's throughout the 80's.
I believe this has been covered quite a bit in other threads so I will refrain from my usual going on and on and on...
