I need to know does the h/light wiring have any type of circuit breaker or cut out other than the fuse or is it not fused? all wiring looks original and in good cond but it has ls2 fitted and lots of things changed but now have problem with lights and dash lights flickering after 1 minute of lights being on, not sure if this is inheired problem or because of mods. Any ideas thanks.Light switch and dimmer, bulbs most everything are new parts

Most headlight switches have a built in circuit breaker. Could be bad switch or overload/short causing breaker to cut out. Good luck, Jim

Just guessing but I'd start looking at ALL the grounds.

Earths are not the problem it has extra ones at rear for pump trans x/ member all been checked sounds like new switch may be faulty