The comment about people's size and expectations for car size changing over time is spot on. Remember these were called the big Healeys after the introduction of the Sprite, and we're considered a mid size, mid-priced sports car.
I have had Healeys big and small, MGBs, and Triumph TRs. The 100 was fine for my 6' long legged frame, but I learned to drive knees splayed out in a Sprite. Shoulder room is better than the others and the ability to put the elbow out at just the right height on the driver door is great on long trips. Once I got cockpit heat under control the 100 was the comfortable car of choice for touring over my brother's TR3 (all things are relative, but I really thought it was pretty nice for a day's drive). I had no problem with steering wheel position or pedals. The only issue was top up driving, getting in and out was not easy, and my head hit the top bows on bumps until I had a couple of inches of foam taken out of the driver's seat cushion.