Hit the river yesterday about 11:30 and realized I hadnt checked the oil in a few trips....so we anchored at our usual spot and decided to check after she cooled and there it was......missing oil filler cap. I looked everywhere for it and can't find it.
Good thing is that there is NOT oil sprayed anywhere and I am not low. Oil pressure was also good.

Did I do any damage running the motor like this?
Needless to say I have spent 20 something bucks to get a cap here this week.

You said pressure was good and you didn't lose any oil? If thats the case, you did no damage.

Running the engine with the filler cap off. . . what a concept!

No damage since no oil spewed.

Won't hurt a thing. You may have some oil film on things to wipe down but that's about it.

if i knew just looking for a thing would cause it to go missing, i would have checked for my ex-wife long before we separated.

You might be surprised how little oil actually is on the rocker arms and pushrods. When I adjusted the valves on my engine, while it was running, I had rags ready to catch tons o' oil, and it hardly any even splattered on the exhaust riser. Now that was at idle, but it was cold idle with 40 psi.

Whats target oil psi at cruise? was around 55-60 correct?

Now thats funny!!!!!

SBC can have just 10lbs per 1000 rpm. Most of the newer ones have a little more than that, so yeah, 50 psi at 3500-4000 is just about normal.

My 1979 Chevy Monza, for which I built a 327 SBC and hooked up to the stock Saginaw 4 speed with the tall rear gears for the four banger Vega block, lost its oil cap and I was quite broke. Ran that puppy for months with a red shop rag stuffed in the filler hole. Man that car flew... Up to about 60mph, then it was screamin' at 5000 RPM.