Some basic FE considerations-----

There has never been replacement aftermarket valve covers made that worked

Your oil pressure line to your guage is too small and will create quite an occislation of readings as rpm varies even slightly with high pressure/volume pump

What fuel pressure and carb ?

Distributer is ported or manifold vacume advance??

Bafffles for the rocker arm assemblies ?????????

Oil restrictor to rockers?

Shaft orientation???

How much vacume does PVC pull at valve??

Is Vent /Cap on left cover baffled??

Carb base plate gasket on correct so as not to block vacume routings?

Cylinder leakdown and/or compression check??

Valve clearance??

what do plugs on 1-4 look like??

What valve seals used??