Same block same cam same lifters- safe to reuse? Setting preload?

I’m looking to reuse the hydraulic flat tappet cam that came out of the engine that I just rebuilt 318 now stroke to 390. I marked and carefully stored everything so that every lifter goes back exactly where it came from. The lifters are still pumped up. The cam is a Crower 224/224 .465 lift. Car came with the 273 adjustable rockers which I was going to reuse. Iron heads which I am reusing as well. How would I bleed the lifters so I can set appropriate preload? Disassemble them? Thanks for the help.