If you really need to rescue a particular block that's ratted out too much for stock 0.875" OD Ford lifters & bushings, you can have Chrysler-sized 0.904" lifters installed with their necessarily huge bushings. I've even heard of custom lifters that are 0.916" OD. On some blocks (like BBCs Chevys with slightly off-center lifter holes and stock 0.843" OD size), oversized Chrysler-type bushings can get perilously close to the side of the cast iron lifter bosses, reducing lifter support with big valve springs. Again, all this IMHO is a pro race machine shop job.
If you do this, you really should change to a custom ground cam to accommodate the enlarged lifter size. Bullet Cams and probably others grind these for Ford & Chev go-fasters. Racers like them because larger dia lifters allows using a more aggressive flat-tappet lift profile and slightly softer springs without risking tearing up cam lobe flanks. Any advantage is largely wasted with roller cams and with street grinds, and a full conversion is quite expensive since it includes a custom cam. But it does work if a new block is out of the question for some reason.