useless conversion, unless you plan some serious engine mods. Retrofitting cable throttle and old-style ISCV only can save you some quid when buying an aftermarket computer.
I am like george and prefer to use the DBW. The 1uz VVti TB with the accelerator position sensor on the TB can be converted over to normal very easy. First of the 3uz VVti take a bit longer and late 3uz VVti are not so easy at all.