I wouldn't worry about that pressure. My old LB7 after 170,000 miles still hits about 80 psi on the gauge at start up, but backs off to 60 after normal temps are reached.
I don't know what the factory oil fill is, but your replacement oil may just flow a little differently. OF course I always run the 5W-40 instead of the 15W-40.
Having said that, if it ever pegs the gauge and keeps it there when its running at operating temperature, I'd suggest you pull over and shut it off and get it towed.
Had that happen with a friend of mine's engine one night coming back from Daytona and the oil gauge pegged and we kept driving and discussing what might be going on. We finally deceided that it had spun a cam bearing and that had closed off the oil flow hole in the block and sure enough one of Rod's started to slightly knock after about 15 minutes and it got louder and louder, finally pulled over about the time it would have blown had we kept going, got it towed to a garage and had to have some serious engine work done on it to get it back home.
I suspect you just have an engine with manufacturing tolerances on the tight end and not the loose end of the tolerance.
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