Going to need more Amps or not?

35-40 Amp Generator is about as big as it gets. Is it actually putting out the amperage?
Should be more than enough. LED lights use a fraction of conventional lighting requirements. Prices are all over the map but can get pricey for LED's. Whether running 12V or 24v, parallel or series,battery capacity needs to be 1000 amp for cranking.

While LEDs do use less power individually they make up for it by cramming more of them in. A 12v 200w LED light bar on your 4x4 still uses the same Amps as two of the old 12v 100w spotlights.

What does the new lighting system consist of? If you replace the old lights with similar size LED versions it will be fine. If you start putting 50inch light bars on it you are going to run into trouble fairly quickly...

leds are more efficient and will lower the power draw provided your staying with the same or slightly higher actual light output. note i said light output not wattage. light is measured in lumens, lux or candle power

or you could fit a gnerator thats been converted to a alternator often called a gene-nator there is a bloke in the states that does this you send him a generator that fits your equipment and he converts it or he can source one and then convert it.

is that generator actually putting out 12v 35 amp or is it a old 6volt unit being made to work at 12v. if it made to work at 12 volt it will only be around16 amp remember doubling voltage halves the current.

you can also do what i am and gut the generator make a new 3 inch longer shaft have it keyed to take the drive gear, use the generator housing as a adapter to support the shaft, fit a 4inch taper lock pulley to the other end of shaft which now protrudes past the end of housing and mount a alternator above it this give the required speed increase and ample power.