Well for what its worth from a Road & Track road test the turning circle on a 3.8S was 33’ 5" with 3.5 turns of the steering wheel lock to lock (power steering car). An English road test (Autocar) of a Mark II quotes a turning circle of 35’ 10" (kerb to kerb) for left turns and 35’ 9" for right turns. Turns lock to lock 5 which must be for non power steering car. And for a 420 (Road & Track figures) turning circle 33’ 6" and 2.75 turns lock to lock.
I removed the steering shaft and the seal. It had a spot on the lower lip that rolled upon install.
I had the original seal that was in good condition. I installed it and so far it’s dry. The replacement seals are so soft and thinner than the original.
I have a new seal set that will arrive tomorrow. I will look the new seal, but may just leave the original installed.
22" rack end to end, no ball joints, I could not find a narrower RHD PAS rack,
I think your compromise is very reasonable - an inch too long is a lot better than the kits offered and you have power. I’ll watch for your results. Now will you use the original PS pump or upgrade? Since I have an alternator conversion, I have been intrigued by electric PS pumps, but have not researched.
Mine was originally manual steering, I have fitted an XJ6 alternator and pas pump, so far so good, got the car running for the first time in 42 years today,
Your PS pump is where an aftermarket AC compressor would usually go. Also, never seen the crankcase breather oil separator pointing to the left side of the engine bay. Usually they point to the right and then connect to a pipe leading to the air intake plenum area. Congrats on getting the engine fired up after all these years.