Soak them with Kroil for a few days, then drive them out from the bottom with a long punch. If you manage to move the lifters up about 1/8" or so, the cam should slide out under them, then you'll have more room to manipulate the lifters. If it's that tight, both the cam and lifters will be junk. Be careful and don't crack the block while you're removing the lifters!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!