OrangeB2400,
I have a pit, love it. Suggestions- 4' is too wide. Mine is 3' and works fine. Mine is 6' deep-too deep and I am 6'. I think about 5'2"-5'4" will be about right for me. The pit is a total of 18' long, with steps at one end. I work on both small cars and a F250 4x4. Mine is filled concrete block, with a 3"x3" angle iron track on top, with the poured concrete floor level with the top of the angle. The angle down both sides gives me a ledge to put the cover. The cover is two 1"x6" oak boards, rough cut, with 3/4"plywood sandwiched and bolted together. I just remove as many as I need to get to what I need to work on. The cover stays on except when a car is over the pit. It is strong enough to drive the front wheel of a Dodge 3500/Cummins down the middle. Bowed a little, boys probably won't do that again. The garage/shop is mine/private/farm so not many people around.
I might have the height for a lift, but like you, I could build a pit. after 10+ years, only thing I would/will change is the depth.