I have a big block oil pump in my small block. It runs @ 40 PSI at 900 rpm and 80 at 3000 rpm.
My machine shop said I made a mistake installing the BB pump, it is not necessary. The adverse effect will be an increase in the wear of the distributor drive gear. Spark scatter will not be an issue unless the worn gear (when it does wear) is not replaced.
the ideal oil pressure has a great deal to do with the clearances in your engine and the type and weight of the oil you run and the tempetures your engine will incounter when stressed. if you are useing a common 10-30w or 15-40w you should have 25lbs at hot idle and it(the engine) should get to at least 55lbs at 5000rpm these are almost minimum preasures for a long bearing life, the ideal I would say would be at least 25lbs at idle and not more than 40lbs at idle and not more than 80lbs at 6000rpm when hot the cars engine will come to no harm from lack of oil if your useing good quality oil that is changed regularly ! the secret to long engine life is lots of clean oil constantly cleaning and cooling the bearings, I personally use a big block standard volume /high preasure pump in my personally engines mostly because the big block pumps have 12 teeth unlike small block pumps that have only 7 teeth so just from a smooth feed angle the big block pump is better designed.,do you need a big block pump? of coarse not but I have never lost an engine with one installed! and to those who say a big block pump will suck your oil pan dry at high rpm( thats b.s look in your valve covers when your engines running at 5000rpm on the dyno,the covers never get even close to1/3 full , also you should know that synthetic oils are able to stand temp. at least 80degs higher than standard petrolium base oils so they are very good insurance against damaged bearings because they lubricate for longer at higher heats and break down much slower. BTW pumps do not cause pressure the resistance to oil flow caused by your engines clearances are what determines the back pressure on your gage, and you can change the reading by changeing the viscosity (thickness) of your oil thiner =lower pressure thicker = higher pressure
just some more info; The correct oil temp. is 215-225 deg. with no more than 260deg. with the engine under stress(racing?) if it goes higher than that(260 deg)you need an oil cooler installed because normal oil starts to break down (another good reason to use synthetics)from prolonged use at higher temps also make sure that you dont over cool the oil if it does not run at at least 215 deg. it cant burn off any water that condenses in the engine when it cools and this water mixed with crud from the combustion proccess can form acids that are not good for you bearings. another little trick is to epoxy a few small powerfull magnets inside your oil pan to pick up super fine metal particals in your oil before they get into the oil pump(you will be suprised at the amount of metalic dust these pick up)