Valve cover air suction valves questions

I picked up a low mile 2001 KZP recently. I removed the valve cover to check valves and because it had leaking end plugs. My question is about the air suction valves. The 2001 had a single gasket on each valve. One came off clean, the other came off in pieces. I had an older non J model engine laying around and removed the air suction valves from it. They seem to have an integral rubber gasket molded around them. Is there a reason they stopped using these? they appear that they would seal much better.I just don't want to hear putt, putt, putt noises when I put it back together and I'm not spending 32.00 each gasket for OEM either. Just curious as to why there are obviously 2 different versions of this valve. The older ones look tight and seal good at the flappers so I'll just try them and see how it goes. I know they make block off plates but I like the originality factor.

The top pic is the 2001 version, the bottom is non J model 1980 or 81 I believe.

Id just use some silicone/rtv and make my own,just let it tack up really good before installing covers

The Kawasaki supplied "Smog Gear" for the most part does not add, Nor subtract horsepower to the engine. Most riders get a block off plate & remove the reed valves, vacuum switch and rubber hoses, making sure to cap off any of the vacuum lines.

APE ( www.aperaceparts.com/tech/techkz1000.html )makes a nice set of block off plates.