You can use just about any expansion spring, you are only holding the valve closed with enough tension to hold the keepers in place while you check your opening and closing events. I use these from Summit in my engines, and not all are 4g63 but I wouldn't think there would be any difference since spring rates don't come into play for that purpose.
Like these, but really you can probably get a couple from a hardware store or such.....

Go to Lowe's.. The end of the hardware sections have 1lbs compression springs.. Use that. Only one will be around the same size of our valvesprings. So you know which to get.. You need only two.... I got way to many.. And make your own adjustable lash adjusters.

Great videos about this subject:

thanks guys, ive been watching jafromobiles videos over and over and think ive wrapped my head around this, just wasnt sure of the size of the test springs. appreciate the help!!