Do post some pictures of your plumbing if you can Priobe.
10 - 15 psi at idle is not good at all, way too low. If it was my engine I would not run the engine until you get the pressure issue diagnosed. If you are running twin filters you should most certainly be using a high
volume oil pump IMHO.
Old dog is dead on with his advice.
Other questions I might ask is are you running restrictor plugs in your heads, what about the condition your valve stem seals, amybe a clogged
oil pump pick up? Possibly a loose seal/connection in the pump pick up attachment area, there is a lot to consider.
If your plumbing is correct and you have the HV
oil pump in place you might want to consider the settings, or lack thereof, of your oil pressure relief valve at the back of the block as well as the pressure relief/bypass setting in your oil pump. I shimmed out the pressure relief spring in the oil pump to boost pressure and eliminated the engines pressure relief valve all together.
With these modifications, at idle, I am seeing 70 psi. In the upper rpm range the OP is right at 100 psi. Many will say this is too high but I would disagree for many reasons, but thats another thread.
Lets see some photos when you get a chance.