Many years ago I bought a used cam out of a 5 gallon bucket full of used cams - The seller picked 16 lifters out of a big Maxwell House coffee can and threw them in (I think I paid $20.00 or $25.00 for the lot). I put the cam and the random lifters in a 383 and drove it maybe 20,000 miles before I sold it still running fine. Does my experience mean that keeping lifters on their original lobe isn't at all important - probably not - but it is a real world example of the fact that it isn't certain doom for your engine if you inadvertently swap a couple. YMMV
