1993 Yz125

I got back into riding a couple years ago and just picked up a sweet little '93 YZ125. Need some low-end help and I read in Eric's book about machining the bottom of the cylinder and different exhast valve parts. Would I feel anything by installing one of the intake spacers? What about a flywheel weight? All of the above? Bike has an FMF pipe and silencer. I ride trails, race TT and MX a dozen times a year or so. Can anyone give me specific recommendations on mods for when I rebuild the the top end? I love the way the bike handles and don't want to give up on it. Thanks....