Hi Alan,
I have done this to my e30, but has cost me far far more than I initially wanted to spend (about £250 all in) but the lights on my e30 now are a bit mental, when running at full power I'm putting out 450W of light, and thats not including the apparent +80% lights in the outers.
Basically, I went with what your thinking, 5.75" H4 outers and 5.75 150W KC Daylighters in the inners. For outers I chose the cibie ones, as they have the best lens design and put some philips xtreme bulbs in them.
I sourced some fittings from america, as their e30s had 5.75" lights as standard, then I rewired the system with decent wire to take the current etc. plus to change from H1 to H4 needed abit of relaying.
So yea, its an expensive route to take, but works extremely well. Only issue is the KC daylighters are hard to come by, but I've seen 150W aircraft landing lights on ebay

I'm sure they would do.
Cars in for its MOT today, hopefully it passes and will be on its first event next Thursday
