Afternoon all. I hope everyone is keeping themselves locked away. I finally sorted the engine; I bought a second hand rocker shaft fully built for £25. Installed today. Started the engine up to a whining noise, realised I needed to readjust the valve clearances. Did that, replaced valve caps and rocker gasket, reinstalled everything and, hey presto, a fully functioning engine. I just can't take it out for a spin yet! Thanks for the advice. Also blanked off the EGR valve. Now off to fix the handbrake and replace the shoes. Stay safe.