i dont think its your oil either, whats sump/ oil pickup does it have fitted? or anything else thats been done? and was it a self build?

its strange that the pressure drops when getting hotter and the ticking sound id say is where your lifters are running dry, maybe something expanding when hot and blocking the oil from going where it needs to?

did you use any gasket sealant on the sump? if so did you use an excessive amount as your only supposed to spread a thin layer as it can come off inside the sump and cause a block