Great speakers!
They need plenty of power. I have the second, updated, series with the alnico woofers (gray cones, not white paper) and I drive them with two MC1000s and one MC500 through the original external crossover. The foam on the four woofers needs to be redone every 8 to 10 years. I had the internal and external crossovers checked and serviced a few years ago, just to make sure they were in spec.
I really enjoy the 43xx series. I also own the 4343 alnico, the 4315B, the 4333 alnico, the 4430 and the 4435. I preferably use McIntosh power amps with them, even though I have a variety of amps.
The 4350s need a fairly large room (at least 50 sqm) and it must be well damped.
Be carefull not to exceed with the listening volume, because they can effortlessly play very loudly, with no distortion, which can be detrimental to your hearing.