Thank you. Agree on the firewall.You should be able to remove the two lower engine to mount bolts and gently lift the engine enough to gain clearance. Do not add any holes to the firewall
I’ll try but it’s so tight even a photo is hard. There’s only about a half inch vI have an RV-4 and have changed the fuel pump several times. It's a bit of a puzzle, but I never had to unbolt the engine. Can you post a picture?