Check my work-Chime in please
That is basically it, DR. Go slow 'just in case' but you really should be OK; your lift is not radical as I recall. Do you have the correct final pushrod that you will use? If not, you are going to have to use something close and compensate the measured clearance number by the amount they are off, multiplied by the rocker ratio.
One thing you have be careful with is the empty hydraulic lifter's pistons being compressed way down in the lifter body if you are using the actual valve springs. This will result in the valves not opening as far as they actually will once the lifters are pumped up. If you could remove the valve springs on #1 and put in some very light springs (from the hardware store), then that issue would mostly go away and the caly is not needed. But if you don't have access to an 'off-the-head' valve spring compressor, then you are going to have work with the actual springs as installed.
With the actual springs, measure to see how far the lifter pistons are compressed down into the lifter body from the retainer clip when the valves are near max lift. Then subtract the amount of lifter preload you expect from that measurement; multiply the resulting number by the rocker ratio and you will have the amount of 'missing valve lift' in this test. Subtract that from the clay thickness left after a cycle to get the actual clearance......clear as mud !? LOL
Alternately, pump 2 lifters up with oil (submerge in a can of oil and pump the piston 'til it becomes solid). Use these on #1 and check during the test to see if they stay pumped up to the top. Now your resulting piston-to-valve clearance will be too tight, by your final lifter preload distance times the rocker ratio.
Light temporary valve springs sure make life easier.... or solid lifters. Hope the above helps