Hydraulic vs. solid camshaft ?

I bought a low mileage ford 302 roller block engine but came with flat tappet camshaft. I put it into my mustang drove it a few times and it needs more power. I’m looking at a few camshafts that are under .480 lift. I’ve been looking at the solid camshafts. So I guess my question is if I use a solid cam. Will it change the push rod length? I’m trying to keep cost down if I can possibly use the old push rods that would be great. Also I have fulcrum rocker arms will that cause any issues? Will I get more hp with a solid?