Flat tappet to solid roller...

Top photo is in neutral, bottom is in gear.

After paying attention to oil gauge today I realized that if I sit at traffic lights it is 30psi in neutral and 25psi in gear. After giving it some serious beating everything goes a bit down to what you see in photos.

Should I expect higher oil pressure with solid cam vs hydraulic cam or no difference?
Your oil pressure is great/normal. Remember that psi will fluctuate with rpm's, so lower rpm's in gear vs idling at a higher rpm will reflect in the psi. Also with heat the oil will thin and the viscosity goes down, the oil psi will show lower. I wouldn't use a HV pump ubless the motor had some loose bearing clearances and a deep pan, they eat hp and heat the oil more. I have sb stroker in my daily , solid roller, full groove mains , ported heads, 10.1 and turns between 6-6700rpm's frequently...and it has a M72 stock replace pump. Last refresh the bearings looked perfect. Holds about 27- 30 psi at hot idle after running it hard and the engine temp stays at 185-190.