If your valve train is really noisy after your lifters are adjusted correctly then chances are you have a worn rocker arm or bent pushrod. All 235/261's are noiser than today's modern engines and noisier than flatheads of the same era but they should be pretty quiet, even with solid lifters. New rocker arms, a smooth rocker shaft, and new or reconditioned push rods and adjuster should make it quiet so it just sounds like 12 sewing machines running in synch and not a box full of hammers dropped down a flight of stairs.
If you want it to still be quieter than replace the valve and side cover with cast aluminum aftermarkets, they absorb the noise a bit better.
My 261 with a good valve adjustment is about the same volume at idle as the six cylinder BMW I have, which has an overhead cam engine with solid tappets.
Expect it to tap a bit when it is cold, it will until everything heats up and the clearances tighten.
Tapping valves are not necessarily bad, they don't cause any additional wear unless they are really loose. Valves that are too tight will blow out the seats in a hurry. If they get too quiet then start to worry.
