I used Enviro-Strip in Tamworth. Its a difficult decision re: dipping vs blasting. I would avoid any pure dipping only services like SPL etc. that use harsher acids to remove the paint. Enviro-Strip use the 400 degree pyrolysis oven-baked approach, and then milder chemical baths to wash, rust remove/neutralize, and coat. Overall I'm happy with how that process worked on the exposed surfaces and more open structures within the shell (you can see above that the inside of the chassis rail I removed was nicely phosphate coated and devoid of rust. HOWEVER, the downside on baking a Z is that so much melted crap collects inside certain areas of the unibody. Look at my past pics showing what was built up inside the doglegs, , rear arches, underfloor rails, etc. This, IMO, is a significant future rust risk if those areas don't get opened up during bodywork and cleaned out like I did.
If I were to do another Z to this degree, I'd seriously look into soda blasting for external shell, with focused harsher media for rust spots. Bake and dip for removable panels though would still be an option.
None of the processes will, IMO, adequately address the surface rust that exists within pretty much all the spot welded seams. The last stage of bodywork after paint, before reassembly, should be to drench every cavity and inner structure with Dinitrol 3125 and ML wax products - you want every gap in all major spot welded seams to be dripping Dinitrol for a fortnight afterwards!