Solid roller lifters...

A few comments.
- doubt that rocker arms are causing a 30 psi oil pressure loss [ unless using veeeeeery thin oil ]. I would be looking elsewhere. Factory oil pumps are over-engineered to allow for eventual engine wear & STILL provide adequate oil pressure.
- don't know where this nonsense about bushing lifter bores comes from. I presume you are using a used block & it provided 000s of miles of trouble free running with the existing bores.
- if the engine size is 440 or less, that cam will be a dog on the street
- lifter oiling for needle roller lifters. Another con job, like oil/FT cam failures. It is an engineering FACT that needle/roller brgs survive on minimum oil. HD, the inventor of needle roller lifters, did not provide pressurised oiling to the lifters & they last forever. Examples abound of roller brgs lasting 000s of miles on scant lubrication, u joints, wheel brgs, alt brgs to name a few.
- I would only used bushed lifters & the best that you can get. Isky comes to mind...A bushing type lifter DOES need a pressure wedge for lubrication. It works like the rod/main brgs.