CB750 comstars and all that

So I bought a CB750 off ebay on impulse...having seen the work of www.caferacerdreams.com.es as I love what they have done to the old CB.

So I have managed to buy an F model, DOHC, meaning twin discs and a disc rear...

Now that does not really fit with my goal of a totally clean under seta area, as my little hydraulic reservoir will ruin it, plus the rerar disc is bigger than the fronts!

So easy i think downgrade to a drum and job done...but there in lies my problem...I can only find an 18" comstar eith drum from a cb550 and the holes on the spokes are more round than mine which are the longer skinnier ones....

PLenty of skinny cb250 drum wheels and disc CB750 wheels ...

So what are my options, can i get a smaller more subtle hydraulic back break with a massive reservoir, or what other source of drum comstars can i use on my bike...??

Appreciate any guidance, new to modifying bikes, done a few old VWs but not done two wheeled stuff...so be gentle with me :-)