would it require a fundamental re-design of the aircraft?
Yes. The Robinsons were built to a price point, originally intended to cost $22,000.
The teetering head is hugely successful in the Robinsons and Bells. It can be sturdy, and is the simplest way to get a rotor head onto a helicopter. If you wanted to make it non-teetering, the price will rise considerably, mainly for the complexity and testing. It cannot have any movement in the lead/lag plane or the imbalance would tear it apart. It can have flapping freedom, and of course feathering. But in the decades of rotorhead development, nobody has made one successfully. Stick with the teeter and the wee-waa and the desire to stay alive with positive g.
This thread is named for the propensity for low-time pilots to take the R22 and others out of their design envelope, with resultant tears and gnashing of teeth.