i had the same idea a few years back and bought a nice set of RS2600/3100 lights - put them in but didn't like the bonnet overlapping the light slightly - so took them out (still in the shed somewhere) , i wouldn't do this conversion without the proper bonnet - it just dosnt look right to me - maybe one day i'll get the bonnet to match my lights

in the mean time i went down the H4 headlights and original spotties converted to Halogen - night into day !!
Paul