Hello from Houston. I want to lower the oil pressure on my 71 383 Cuda that pegs the dash gauge when cold and only comes down slightly when hot. I installed a spring gauge and confirmed 80+ cold and around 80 hot. I had a friend rebuild the engine in 95 and he put a high pressure oil pump (M63HP) on it and I run 10-30 oil. I found an old post on this site that discussed oil types and high volume pumps but not high pressure pumps ( https://board.moparts.org/ubbthreads/ubbthreads.php/ubb/showflat/Number/4589685/site_id/1 ). O'Reilly sells three different pumps, standard, high volume and high pressure.

Why high pressure over high volume or even a standard pump?

The old post mentions adjustable springs for pressure, do they still sell these?

What oil type? Can I, should I consider synthetic?

In addition to all this the engine has a knock which is another post but I will see if an oil pressure reduction affects it.

Thanks, Kevin