I had the “privilege” of de-coking a TS3 in a Commer tractor unit back in the early 70’s. I can’t remember if I was still an apprentice or just out of my time (not that it matters) but I do remember making a frame to sit on the tyres at each side of the motor because of the amount of time taken laid half in and half out of the cab scraping the carbon out of the ports. Thankfully one of the other mechanics had experience on the Commers and told me about making a frame that sat on the tyre so you could support your legs. Otherwise you had to lay on the cab floor with the drivers seat removed with your legs dangling which did prove back breaking even to a young lad.
They were quite a reliable engine in the lighter end of the market best suited to the 10 - 16 ton rigid market or 20 -24 ton tractor unit market of the late 60’s and very early 70’s.