CBR F2 Conversion('87 VFR700F2): Two Different Brake Master Cylinders In Use?

Hello,

I've been working on my CBR F2/F3 fork-brake-wheels conversion for a while now. At present I'm having an issue with nailing down which front brake master cylinder bore size I need. There are two sizes floating around, marked either 5/8, or 1/2. Strangely the Honda parts fiche shows only one bore size (indicated by having only one rebuild set part number) for all the F2s through the '96 model year F3s. But there are in fact two sizes out there...My calipers are standard F2 items, and the seal set I ordered for a '94 fit perfectly fine. can anyone help shed some light on this? My local Honda dealership had little to offer of this problem.

Also, on a related issue, for the back wheel there's been some questions going around about the best way to handle the rear brake setup. it seems most people either get their original VFR caliper bracket cut and re-welded, or butcher a CBR bracket. I can tell you definitively that the far better way, as suggested briefly by another (who's name I've forgotten, sorry), is to use the 1st generation CBR (Hurricane) caliper bracket. Relatively simple modifications are required to make it work-just having the axle hole bored to the correct size, and coming up with the correct spacers-and nothing else. This installation is cleaner and potentially far safer than using a welded up part. Just FYI...