Tuning with jets, Power valves and an O2 guage

I've been busy with other stuff, but I'm still curious if I can get this thing tuned right.
I have been looking at some other threads elsewhere on tuning. I read where it was suggested to run smaller jets for leaner cruise A/F numbers but then enlarging the Power Valve Channel Restriction. Sounds good to me. I haven't tried it yet but I'm tempted to buy another metering block to modify, OR....
I have several Holley metering blocks to practice with. I'd prefer to screw up with a throwaway piece.