Valve Springs

^^^ that
When an engine is shut off, there are always valves that remain open. If they sit for very long periods this way,under stress, it can't be good for them. And the next time, perhaps different valves remain open. So eventually several or many valves may lose pressure from the original install. If you buzz it up in this condition there's a good chance of getting into premature valve float,and lifter pump-up,especially with just the outer springs installed. float can initiate lobe damage.When in doubt, replace. Or at the very least, have them checked.
I too have a Hughes HE3038 in my 360. I've also had the HE2430. I love them both. The 292/509Purple was not a good choice for a streeter with a M/T.