I know what you mean, I went through that problem too. You'd have to put the lifters in and then put all the valves in, wouldn't have to put the clips in though. Push the valves down good and measure the gap. .013 -.014 if I remember right. If you're lucky a few will be good.You might be able to switch some to get a few more good ones. Then you'd have to mark the rest with the position and amount to be taken off and take them to a machine shop with a surface or valve grinder. Taking some off the botom increases the gap, taking some off the mating surface decreases the gap (naturally).
Maybe some of those adjustable lifters are better, the ones I had were just a fine thread bolt screwed into the top of a short lifter. I couldn't see how that would last long.